LESSON PLANS - i teach bio

LESSON PLANS��UNIT 1

INTRODUCTION TO MARINE SCIENCE

UNIT 2KINGDOMS OF LIFE IN THE SEA

UNIT 3MARINE INVERTEBRATES

UNIT 4MARINE VERTEBRATES

UNIT 5THE WATER PLANET

UNIT 6ENERGY IN THE OCEAN

UNIT 7MARINE ECOLOGY

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UNIT 1 INTRODUCTION TO MARINE SCIENCE

Chapter 1 /Exploring the Oceans

INTRODUCTION

In Chapter 1, the student learns about the history of ocean studies and travels, from exploratory worldwidesailing voyages to pioneering voyages into the ocean’s depths. The story of the Titanic is told to introduce thestudent to concepts—such as buoyancy—that are related to early ocean travel and to the more recentadvances in technology that have enabled greater exploration of “inner space.”

■ The incentive for early ocean travel was usually the search for new trade routes, riches, and knowledgeabout new lands.

■ Technological innovations have increased scientific exploration of the oceans, facilitating charting of cur-rents, location of shipwrecks, and investigations into deep-sea life-forms and seafloor features.

LESSON 1 (page v: To the Student)

Aim: What is marine science?

Instructional Objectives

Students will be able to:

1. Define marine science.

2. Distinguish between marine biology andoceanography.

3. Explain why Earth is called a water planet.

Motivation for the Lesson/Do Now

Show the class a map of Earth. Have each studentmake a simple sketch of the oceans and conti-nents.

Development of the Lesson

1. Have one student spin a globe of Earth whileanother student (blindfolded) points to a spoton the globe. Repeat 10 times. On average, 7

out of 10 times, the spot touched will be anocean.

2. KEY QUESTION: Why is Earth called a “waterplanet”? Ask students to estimate what per-centage of Earth’s surface is water. Tell themthat the ocean covers about 71 percent ofEarth’s surface.

3. WRITE THE AIM: What is marine science?Explain that marine science is a field of knowl-edge about the ocean, composed of marinebiology and oceanography.

KEY QUESTIONS: What is marine biology? Whatis oceanography? Marine biology is the study oflife in the ocean. Oceanography is the studyof the physical characteristics of the ocean,such as temperature, pressure, density, salin-ity, light, sound, and movements of oceanwater.

4. Do one or more of the following activities toshow how various scientific disciplines tie inwith a study of the oceans: show a photographof a scuba diver to introduce the idea of pres-sure underwater (physics); discuss recentdroughts, floods, and El Niño to illustrate the

4 Marine Science Teacher’s Manual

influence of oceans on climate (meteorology);make “ocean water” by mixing sea salts withfreshwater (chemistry). List and define on theboard the following fields of science: biology(study of life); chemistry (study of matter in itsmolecular form); physics (study of energy andforces); geology (study of formation and struc-ture of Earth); meteorology (study of weatherand climate); and astronomy (study of objectsand matter in outer space).

Summary of the Lesson

Marine science is an interdisciplinary field that isconcerned with the study of the ocean and all theliving things found in it. This study encompassesresearch in the major scientific fields, such as biol-ogy, chemistry, physics, and Earth and space sci-ences. Students will learn that the oceans have agreat impact on life on land as well as on life inthe water.

Homework Assignment

Read page v (To the Student) and pages 3–6. AnswerSection Review questions 1–3 on pages 6–7.

LESSON 2 (pages 4–6)

Aim: Why did the Titanic sink?



1. Define buoyancy (and Archimedes’ principle).

2. Explain why some objects sink, while othersfloat.

3. Explain what happened to the Titanic when ithit the iceberg.


Drop a coin such as a quarter and a ball of alu-minum foil into a large container of water. Havestudents observe what happens to each object inthe water. They should note that (although both

are metallic) one objects floats, while the othersinks.


1. Ask students to drop different items into thecontainer of water, such as a paper clip, cork,pencil, pen, eraser, and so on.

KEY QUESTION: Why do some objects float,while others sink? The coin sinks because itweighs more than the water it displaces. Thealuminum-foil ball floats because it containsair within its folds. Air weighs less than water;so the ball weighs less than the water it dis-places.

2. WRITE THE AIM: Why did the Titanic sink?Have students examine the illustration ofArchimedes’ principle in Figure 1-1 on page 6.

ASK THE CLASS: (a) How much does the objectweigh in air? (35 grams); (b) How much does itweigh in water? (15 grams); (c) What is theapparent loss of weight in water? (20 grams).

3. Introduce the concept of buoyancy. Theancient Greek scientist Archimedes discoveredthat floating objects are supported by anupward force called buoyancy. He stated that (a)the buoyant force on any object is equal to theweight of the liquid that the object displaces;and (b) an object immersed in a liquid appearsto lose weight, and that apparent weight lossis equal to the weight of the liquid displaced.These ideas are known as Archimedes’ principle.

4. KEY QUESTION: How does Archimedes’ principleexplain how the Titanic sank? A steel ship floatsbecause it is constructed to have many air-filled compartments. The Titanic sank becauseits air-filled compartments filled with waterafter a collision with an iceberg. The addedweight of the water combined with the weightof the ship became greater than the buoyantforce supporting the ship, thus causing it tosink rapidly.


An object sinks when the weight of the object isgreater than the buoyant force that supports the

UNIT 1 / INTRODUCTION TO MARINE SCIENCE 5

Explorer/Navigator Country of Origin Lands Explored

The Vikings Scandinavian countries Newfoundland, Canada

Batholomeu Dias Portugal South Africa

Christopher Columbus Spain/Italy Bahamas

John Cabot England Labrador, Canada

Vasco Núñez de Balboa Spain Panama

Ferdinand Magellan Portugal Americas to Philippines

Giovanni da Verrazano Italy North America (east coast)

Jacques Cartier France Canada (east coast)

object. An object floats when its weight is lessthan the buoyant force that supports the object.

Homework Assignment

Answer Chapter Review questions 9–12 on page24. Read pages 7–10 (top of page). Answer SectionReview questions 1–3 on page 10.


Aim: What is known about the early oceanexplorers and navigators?



1. Identify the early ocean navigators and oceanexplorers.

2. Describe the accomplishments of these earlyexplorers.

3. Explain what motivated the early explorers totravel by sea.


Have students review pages 7–10 in their text-books; ask them to look at Figure 1-2 on page 9,which illustrates the path of Magellan’s historicattempt to circumnavigate the globe.


1. Organize the class into eight groups, each witha team leader. Walk around the room andhave each team leader choose from a con-tainer a piece of paper that has the name of anearly navigator or explorer on it.

2. WRITE THE AIM: What is known about the earlyocean explorers and navigators? Students shouldcomplete their review of pages 7–10. Then stu-dents should write as much information aspossible in their notebooks about their group’sassigned explorer. When they are ready, havethe team leaders go up to the board to recordthe facts on a chart, as shown below. (Checkfor accuracy.) All students should copy thecompleted chart into their notebooks.

3. KEY QUESTION: What were the routes taken bythe early navigators and explorers? Distributecopies of world maps on which students candraw lines to show the approximate pathssailed by each explorer. Have students writethe appropriate explorer’s name on each line.

4. KEY QUESTION: What have you learned aboutthe early explorers? Have each group prepare abrief summary. Call on a student from eachteam to read their summary aloud to the class.


A sense of adventure, combined with the oppor-tunity to expand trade routes, conquer lands, and


Scientific Ocean Explorer Scientific Achievement

Capt. James Cook (mid-1700s) Observed that citrus fruits prevent scurvy

Benjamin Franklin (in 1770) Had first map of the Gulf Stream drawn

Charles Darwin (in 1830s)) Observed species on Galápagos Islands

Matthew Fontaine Maury (in 1855) Wrote The Physical Geography of the Sea

Sir Charles Thompson (in 1870s) Compiled 50-volume Challenger Report

Fridtjof Nansen (in 1890s) Invented a water-sampling instrument

obtain great wealth, motivated the early explor-ers to search for new lands by sailing the oceans.

Homework Assignment

Read pages 10–13. Answer Section Review ques-tions 1–3 on page 14 (at top of page).


Aim: What do we know about the early sci-entific exploration of the ocean?



1. Identify the early ocean scientists.

2. Describe the achievements of the earlyoceanographers.

3. Explain what motivated the early ocean scien-tists.


Have students review pages 10–13 in their text-books. Briefly discuss the Discovery feature aboutthe unusual ocean voyages of Thor Heyerdahl.Elicit answers to the three questions that arebased on the feature (see page 12).


1. Organize the class into six groups, each witha team leader. Walk around the room andhave each team leader choose from a con-tainer a piece of paper that has the name of anearly ocean scientist on it.

2. WRITE THE AIM: What do we know about theearly scientific exploration of the ocean? Studentsshould complete their review of pages 10–13.Then students should write as much informa-tion as possible in their notebooks about theirgroup’s assigned ocean scientist. When theyare ready, have the team leaders go up to theboard to record the facts on a chart, as shownbelow. (Check for accuracy.) All studentsshould copy the completed chart into theirnotebooks.

3. KEY QUESTION: What did Benjamin Franklindiscover about the Gulf Stream? Have studentslook up information on the Gulf Stream intheir textbooks. Have students draw the pathof the Gulf Stream across the Atlantic Ocean.

4. Key Question: What conclusions can be drawnabout interest in the ocean from our study of earlyoceanographic exploration? Have each groupprepare a brief summary of their findingsabout early ocean scientists. Call on a studentfrom each group to read it aloud to the class.


The early ocean scientists continued in the pathstarted by the early ocean navigators. However,


Correct IncorrectTrial Amount Amount

1

2

3

4

Total

Average

the scientists sailed in the quest for knowledge,rather than in a quest for wealth or new lands.

Homework Assignment

Read pages 14–18 (top of page). Answer SectionReview questions 1–3 on page 18.


Aim: What is known about the history ofinner space exploration?



1. Describe how the early divers explored under-water.

2. Explain, briefly, how scuba gear works.

3. Identify a few pioneers of underwater explo-ration.


Display some snorkeling and/or scuba divingequipment. Ask students to describe vision under-water, with and without the use of a facemask.


1. Elicit from students that a diver’s vision isblurred underwater. A facemask is required inorder to see objects clearly underwater.

WRITE THE AIM: What is known about the his-tory of inner space exploration? The earliest-known instances of underwater, or innerspace, exploration occurred 4500 year agowhen ancient Greeks, using newly developedglass, made crude facemasks to help them seebetter when diving for ornamental shells.

2. KEY QUESTION: How can we show that it is dif-ficult to see underwater without a facemask? Placea dollar’s worth of change at the bottom of abucket of warm water. Ask a few student vol-unteers to look underwater without a face-mask (and without contact lenses) to try todetermine the correct amount of change. Doseveral trials. Have another student record theresults in a data table on the board by writinga check mark in the appropriate column (cor-rect vs. incorrect amount guessed). Determinethe percent correct.

3. KEY QUESTION: How did diving technologyevolve over the years? Refer students to Figure 1-4 on page 14. One of earliest devices made forstaying underwater was the diving chamber, ahuge barrel that contained a limited supply ofair. Simulate a diving chamber by putting asmall beaker upside down inside a largerbeaker half-filled with water.

4. Discuss advances in diving technology. Thediving suit came next; it was made of water-tight canvas with a heavy metal helmet, orhard-hat. Air was pumped from the surfacethrough a tube into the helmet. The laterdevelopment of the scuba tank, or aqua-lung,gave divers greater freedom of movement.(Have students refer to Figures 1-5 and 1-6 onpage 15.)


Advances in diving technology (especially in thepast 150 years) have given people the ability to


explore the ocean at greater depths, for longerperiods of time, with more safety and mobility.

Homework Assignment

Read pages 15 (bottom)–20. Answer SectionReview questions 1–3 on page 20.


Aim: How was the Titanic located?



1. Explain how the Titanic was finally located.

2. Describe some of the technology used in locat-ing the Titanic.

3. Identify other technologies used in underwa-ter exploration.


Ask students why scuba divers were not used totry to locate the resting place of the Titanic.


1. The crushing effects of deep-sea pressure and alimited air supply prevent scuba divers fromattaining great depths.

WRITE THE AIM: How was the Titanic located?Show the class pictures of submersibles, thesteel-hulled vehicles that are designed forunderwater research. A submersible’s thickhull and larger air supply enable researchers todive deeper.

2. KEY QUESTION: How well did people exploreusing the early submersibles? In 1934, Americanoceanographer Dr. William Beebe reached adepth of 900 meters in a steel chamber calleda bathysphere. In 1960, the Swiss team of

Auguste and Jacques Piccard made the deepestdive in a submersible to the bottom of theMariana Trench (10, 852 meters).

3. KEY QUESTION: How do the modern sub-mersibles explore the ocean floor? American sci-entists have logged more than 900 divesaboard the submersible Alvin. (See Figure 1-7on page 17.) In 1979, Dr. Sylvia Earle set arecord for making the deepest solo dive,attaining a depth of 380 meters while in thehigh-tech personal submersible called the Jimsuit.

4. Unmanned vehicles, called robots, are used forexploring in the deepest parts of the ocean.The robot Argo was tethered to a surface shipand used to photograph the Titanic. (See Fig-ure 1-9 on page 19). The robot Jason, tetheredto the Alvin, photographed the Titanic’s inte-rior.

5. KEY QUESTION: How is ocean depth determined?Ships use the technology of sonar (sendingand receiving sound waves) to determineocean depth and to locate objects on theseafloor. Sonar stands for sound navigationand ranging.

6. KEY QUESTION: Who located the resting place ofthe Titanic? Using a combination of sonar androbot technology, the U.S.–French team led byDr. Robert Ballard and Jean-Louis Michel wasable to find the Titanic in 1985, resting 3600meters deep on the North Atlantic seafloor.


The development of advanced technology, in theform of submersibles, robot vehicles, and sonarequipment, has culminated in such achievementsas finding the sunken Titanic 3600 meters deep.

Homework Assignment

Answer Chapter Review questions 6–8 on page 23and 13–23 on pages 25–26.


Chapter 2 /Marine Scientists at Work

INTRODUCTION

In Chapter 2, the student is introduced to the world of scientific research, particularly that of marine science.The scientific method is explained as the procedure by which scientists conduct valid research. Units of scien-tific measurement are discussed. Special characteristics of ocean water, such as salinity and density, areexplained in relation to measurement procedures. The use of scientific tools for making accurate measure-ments and observations is discussed; different types of microscopes are described.

■ While conducting research and experiments, scientists use a problem-solving approach called the scientificmethod, an organized way to gather, investigate, and present their data.

■ Scientific resources, tools, procedures, and measurements are important elements in the lab work andfieldwork of a marine scientist.


Aim: What is the scientific method?



1. Define the scientific method.

2. List the steps in the scientific method.

3. Formulate and test a hypothesis.


Show the class some live mud snails (Ilyanassa) incontainers of ocean water. Have the class make alist of observations about the snails.


1. Have a few students write their observationsabout the snails on the board. For example:snails move; snails respond to touch; snailshave a shell; and snails use a muscular foot forlocomotion. Next, ask students to identify sci-entific problems that can be generated from

their observations. For example: How fast is asnail? Does the presence of food in the wateraffect the speed of a snail?

2. WRITE THE AIM: What is the scientific method?Explain that an organized step-by-stepapproach, called the scientific method, is usedto solve problems. The main steps in the sci-entific method are: (a) making observations;(b) stating the problem; (c) forming and test-ing a hypothesis; (d) selecting the materials;(e) designing a method or procedure; (f)obtaining results; and (g) drawing conclusions.

3. KEY QUESTION: Can you formulate a problemrelated to food and locomotion (in snails)? Writeon the board the following problem: Doesfood affect the speed of a snail?

4. KEY QUESTION: Can you offer a possible solutionto this problem? Formulate an educated guess,or hypothesis, to explain the movement ofsnails. Hypothesis: If food is in the aquarium,then the snails will move with greater speed(toward the food) than if food is not present.

5. KEY QUESTION: What materials are needed totest this hypothesis? Make a list on the board(under the term Materials) of the equipment orapparatus needed to solve the problem. Forexample: aquarium tanks, ocean water, gradu-ated cylinders, marine snails, and food.


6. KEY QUESTION: How should the materials beassembled to solve the problem? The materialsare assembled according to the set-ups shownin Figure 2-5 on page 35. Have students referto this illustration.


There are many topics to be studied in marine sci-ence, and many tools (e.g., remote sensors) andinstitutions that aid in this research. Althoughpeople can investigate different topics in marinescience, all scientists propose, hypothesize about,and research their problems in much the sameorganized way—generally known as the scientificmethod.

Homework Assignment

Read pages 27–32; answer Section Review ques-tions 1–3 on page 33. Then read pages 33–36.


Aim: How is the scientific method used tosolve problems?



1. Analyze data in a table and in a graph.

2. Interpret the results of an experiment.

3. Conclude whether a hypothesis is to beaccepted or rejected.


Give all students a copy of Table 2-1 (see page 36),and ask them to compare the data for the experi-mental and control groups. Have students calcu-

late the average speed for each group of snails.(Give them the formula: Speed = distance/time).


1. Review the “Do Now” with your students.

WRITE THE AIM: How is the scientific methodused to solve problems? Introduce the terms con-trol group and experimental group. Explain why ascientific experiment includes both groups (totest the variable and to ensure valid results).

2. The measurements that are made in an exper-iment are called data. The data collected makeup the results. The results can be recorded in adata table. A table format makes the data betterorganized and easier to interpret. Each time anexperiment is carried out, it is called a trial.More than one trial should be performed in anexperiment. The average of many trials givesa more accurate result than just one or twotrials.

3. KEY QUESTION: How can data be displayed?The results of an experiment can be displayedin the form of a graph. A graph shows rela-tionships at a glance. Two kinds of graphs arethe bar graph and the line graph. (Have stu-dents refer to Figures 2-6 and 2-7 on page 38.)Both graphs use two lines, or axes, to displayrelationships between sets of scientific data—the vertical axis (y-axis) and the horizontal axis(x-axis).


The scientific method is used when researcherscarry out an experiment, organize the data theygather, and interpret the results. Data are orga-nized in data tables and/or in line or bar graphs.

Homework Assignment

Read pages 36–39 and 42–45 (top of page).Answer Section Review questions 1–3 on page 45.


Chapter 3 /Marine Environments

INTRODUCTION

In Chapter 3, students will learn about marine life zones, about the four major types of marine environments,and about the different communities of organisms that are characteristic of those environments. Sandy beachand rocky coast environments are described and compared. The various communities found within estuaryenvironments are described, i.e., salt marsh, mud flat, and mangrove. Finally, the coral reef environment isexplored, with special attention given to the physical and behavioral adaptations of its diversified inhabitants.

■ Coasts and oceans are composed of specific life zones. In each zone, there are characteristic groups ofplants and animals, which have adaptations that are suited to survival in those areas.

■ Factors such as substrate, wave action, and salinity affect the kinds of organisms that can live in a particu-lar marine environment.

■ Wetlands are nutrient-rich, biologically productive communities.

■ Coral reefs are massive stony structures that form the basis for complex, productive, and biologically diver-sified communities in tropical seas.


Aim: What are the major life zones in theocean and along the coast?



1. Identify the major marine life zones.

2. Visualize the zones geographically.

3. Describe the characteristics of the life zones.


Show students a world map and ask them todescribe the parts of the ocean that they thinkcontain the most life and the least life.


1. A life zone is a region that contains specificorganisms that interact with one another andwith their environment. The surroundings of aliving thing are called its environment.

WRITE THE AIM: What are the major life zonesin the ocean and along the coast?

2. Draw on the board a profile of the coast andocean, going from the supratidal zone to theoceanic zone. Refer to Figure 3-1 on page 62,and Figure 3-3 on page 64.

3. Imagine walking from the upper part of asandy beach down to the sea, and then boat-ing out to sea for a short distance.

KEY QUESTION: What major marine life zoneswould you pass through? Write on the board thefollowing zones after identifying them on thediagram.

■ Supratidal zone: an area of the upper beachthat gets a fine mist of salt spray from thecrashing waves. Has beach plants, includ-ing grasses, shrubs, and trees.

■ Intertidal zone: the turbulent area betweenhigh tide and low tide, where clams, barna-cles, mussels, worms, and seaweeds live. Along line of seaweed called the strandlinemarks the high tide on beaches. (See Figure3-2 on page 63.)

■ Subtidal zone: the area below the intertidalzone. This zone includes the surf zone, anarea of wave turbulence. Fish, crabs, seastars, and sea urchins are typical inhabi-tants of this zone.


■ Neritic zone: lies above the continental shelf,the shallow part of the seafloor that sur-rounds the continents. It is the main areaof commercial fishing.

■ Oceanic zone: extends beyond the neriticzone and includes most of the open ocean.Together, the neritic and oceanic zonesmake up the largest marine life zone, i.e.,the pelagic zone. The upper part (or photiczone), which most light penetrates to about100 meters, contains more life (due to pho-tosynthesis by algae) than does the vastarea below it (i.e., aphotic zone), whichremains in darkness.

■ Benthic zone: includes the entire oceanfloor, from the intertidal zone to the oceanbasin. Organisms that live on the seafloorare called benthos. Benthic organisms oftenshow unique adaptations to conditions onthe ocean floor.

4. Have students copy into their notebooks thelabeled diagram of the marine life zones.


The ocean contains several different life zones,each one characterized by particular communitiesof plants and animals that are adapted to live inthose environments. Have students write in theirnotebooks a brief description of each life zone dis-cussed in the lesson.

Homework Assignment

Read pages 60–67 (top). Answer Section Reviewquestions 1–3 on page 67, and Chapter Reviewquestion 7 on page 89. Complete the labeled dia-gram of the major ocean (and coastal) life zones.


Aim: What do we know about the sandybeach environment?



1. Describe the sandy beach environment.

2. Identify the life zones of a sandy beach.

3. Discuss interactions of organisms and theenvironment.

Motivation for the Lesson /Do Now

Describe the characteristics of a sandy beach (orshore). Look at Figure 3-5 on page 69, whichshows the surf zone on a sandy beach. Ask stu-dents: Why is the water white? Explain.


1. When waves crash on a beach, air mixes withthe water, producing white foam. The regionwhere waves crash on a beach is called the surfzone. The surf zone is a characteristic featureof a sandy beach.

2. WRITE THE AIM: What do we know about thesandy beach environment? The sandy beach envi-ronment contains loose, unstable sediment(i.e., sand), which is easily moved about bywind and water. Beaches that are characterizedby large surf (i.e., breaking waves) are thosethat face the open ocean. The surf zone is nota fixed zone. It moves with the tide as itadvances and retreats up and down the slopeof the beach.

3. KEY QUESTION: What kinds of organisms arefound on a sandy beach? Project Figure 3-1 (seepage 62) on the overhead. Note the distinctlife zones in which groups of organisms arefound. On the upper beach, e.g., there is azone of beach plants that includes trees,shrubs, and grasses. The roots of these plantshold the sand in place, preventing its erosionby wind and water, and forming small hillscalled dunes. The trees occupy the highest ele-vation in the dunes, followed by shrubs grow-ing along the slopes, and then beach grassesat the lowest part of this (upper supratidal)zone.


4. KEY QUESTION: How are marine animalsadapted to life in the surf zone? Organize theclass into groups of three to four students.Have the students read their textbooks to findinformation on the following organisms: molecrab (pages 68–69), blue claw crab (page 69),and silverside fish (page 69).

■ Mole crab (Emertia): has smooth jellybeanshape that helps it swim through sand andwater; avoids wave impact by digging intothe sand with its paddlelike appendages;feeds on microscopic organisms by stickingits feathery appendages up into the water.

■ Lady crab (Ovalipes): swims and digs intothe sand by means of its paddlelikeappendages; hides from predators by bur-rowing in the sand, leaving just its eye-stalks exposed.

■ Silverside fish (Menidia): small fish thatswims in schools in the well-oxygenatedwaters of the surf zone; feeds on inverte-brates and crab eggs; are preyed upon bylarger fish such as the striped bass (Morone).


Ask a student leader from each group to readaloud the information obtained by their group.Ask another student to write a brief summaryabout each animal on the board. Have studentscopy the completed information into their note-books.

Homework Assignment

Read pages 67–69. Answer Section Review ques-tions 1–3 on page 69.


Aim: What kinds of marine life are found ona rocky coast?



1. Describe the zonation on a rocky coast.

2. Compare and contrast a rocky coast with asandy beach.

3. Identify typical rocky coast marine organisms.


Show students some beach sand; then show stu-dents a rock that has barnacles or other marineorganisms attached to it. Ask students: In whichenvironment are more organisms found—a sandybeach or rocky shore? Explain.


1. Shores made of solid rock, called rocky coasts,provide stable substrates on which organismscan attach. The irregular topography of therocky coast, with its coves, crevices, and tun-nels, also provides hiding places for marinelife. Show the class a map of the United States;point out areas that have rocky coasts, e.g.,Alaska, California, Maine, Oregon, Washing-ton, and Hawaii.

2. WRITE THE AIM: What kinds of marine life arefound on a rocky coast? Project Figure 3-8 (seepage 71) on the overhead. Note that the char-acteristic organisms inhabit distinct bands, orlife zones, along the coast. These bands of dif-ferent communities in an environment makeup a feature known as zonation. From the dis-tance, these zones have a layered appearancewhen the tide is low (refer to Figure 3-7 onpage 70).

3. The rocky coast zones are divided into theupper intertidal, the mid-intertidal, and the lowerintertidal zones. Organize the class into groupsof three to four students. Have the studentsread their textbooks to find information onthe following rocky coast life zones: upperintertidal (pages 70–71), mid-intertidal (pages72–73), and lower intertidal (page 73). The fol-lowing information should be covered:


■ Intertidal zone: is above the high-tide mark,receives wave splash; blue-green bacteriaand algae grow on the moist rocks; whenalgae die, they stain the rocks black; peri-winkle snails and limpets graze on thealgae.

■ Mid-intertidal zone: is inhabited by barna-cles, mussels, and seaweeds; barnaclesattach to the rocks by means of a naturalglue; mussels produce sticky byssal threadsthat adhere to the rocks; rockweeds adhereto rocks by means of a holdfast attach-ment; at high tide, barnacles filter feed onplankton; at low tide, barnacles close theirshells to avoid drying out.

■ Lower intertidal: is dominated by seaweeds;at low tide, spaces between the rocks retainwater, forming small living communities(of algae, invertebrates, small fish), calledtide pools. When the tide is in, sea stars, seaurchin, and fish invade this zone to feed.


Have a student leader from each group read aloudthe information their group has obtained. Askanother student to write a brief summary abouteach life zone on the board. Have students copythe completed information into their notebooks.

Homework Assignment

Read pages 70–74 (top). Answer Section Reviewquestions 1–3 on page 74, and Chapter Review question 6 on page 89.


Aim: Why is the estuary considered such avital marine environment?



1. Describe what an estuary is.

2. Explain why estuaries are important.

3. Identify the communities in an estuary.


Sketch on the board or project on the wall a pic-ture of the mouth of a river, i.e., an estuary (e.g.,the Hudson River entering the ocean at the Nar-rows, in New York City). Ask students: Why isthis area so vital to marine life?


1. The area along the shore where a river entersthe ocean forms an environment called theestuary. In the estuary, freshwater from theriver mixes with salt water from the ocean,forming what is called brackish water.

2. WRITE THE AIM: Why is the estuary such a vitalmarine environment? Draw on the board, orproject on an overhead, a cross-sectional dia-gram of an estuary (see Figure 3-10 on page74). Estuaries provide varied habits for marinelife. Many estuaries have large offshore sand-bars called barrier beaches. The barrier beachseparates the ocean from the bay, creating nat-ural sanctuaries for communities of aquatic(and terrestrial) animals.

3. KEY QUESTION: What kinds of biological com-munities are found in the estuary? Organize theclass into groups of three to four students.Have the students read their textbooks to findinformation on three kinds of estuary (andshore) communities: salt marsh (pages 75–77),mud flat (pages 78–80), and mangrove swamp(pages 80–81). The following informationshould be covered:

■ Salt marsh: also called wetlands; its domi-nant species are the marsh grasses; the tallmarsh grass Phragmites, with its brown tas-sels, grows in the upper supratidal zone;tough cordgrasses (Spartina) grow in theshallow waters and provide a haven formarine invertebrates and fish; when cord-grass dies, it forms dead matter, or detritus,which supplies nutrients for plankton; the


plankton are the basis of marine foodchains, many of which originate in the saltmarsh.

■ Mud flat: is like the graveyard of the estu-ary; the sand is dark and contains organicdebris carried in by the incoming tides;decomposers are abundant; bacteriadecompose the wastes and turn them intothe foul-smelling compound hydrogen sul-fide (H2S); invertebrates such as the mudsnail (Ilyanassa) scavenge for food; inhabi-tants include a variety of worms and clamsthat burrow in the muddy sand, such asthe clam worm (Nereis), the razor clam(Ensis), and the soft-shell clam (Mya); vari-ous shorebirds prey on these invertebrates.

■ Mangrove swamp: the dominant species isthe mangrove tree (Rhizophora), whichgrows in tropical regions (like Florida); athick growth of mangrove trees lines theshores of bays and inlets, forming a man-grove community; the trees have archingprop roots, which anchor the trees and pro-vide a haven for a variety of marine ani-mals; inhabitants include the crown conch(a marine snail) and the mangrove snapper(a marine fish). Mangrove swamps protectthe shoreline from erosion, and act likegiant sponges, absorbing the water andimpact of tropical storms.


Have a student leader from each group read aloudthe information their group has obtained. Askanother student to write a brief summary abouteach coastal community on the board. Have stu-dents copy the completed information into theirnotebooks.

Homework Assignment

Read pages 74–81. Answer Section Review ques-tions 1–3 on page 82 (top), and Chapter Reviewquestion 8 on page 89.


Aim: Why is the coral reef considered to bean underwater oasis?



1. Explain why the coral reef is an importantmarine environment.

2. Identify the typical inhabitants of a coral reef.

3. Describe interrelationships among the reefinhabitants.


Display or project on an overhead a photographof a coral reef. Ask students to count and identifyas many living things as possible that are visibleon the reef.


1. There are probably at least a dozen (readily vis-ible) different species of living things found ona small patch of reef.

WRITE THE AIM: Why is the coral reef consid-ered to be an underwater oasis? The coral reef islike an “oasis” because it contains a fantasticassortment of marine life in what otherwisewould be an area of low biodiversity. Coralreefs are found in tropical and subtropicalregions (between 30 degrees north and 30degrees south latitude). Warm, clear, sunlit,shallow ocean waters are necessary to promotethe growth of coral reefs. Together, the hardcorals and soft corals on a reef provide a variedhabitat for marine life.

2. KEY QUESTION: What kinds of marine organ-isms inhabit a reef? Organize the class intoseven groups, with each team reading in theirtextbooks about one of these typical reeforganisms: staghorn coral (pages 82–84), spot-ted trunkfish (page 84), schooling reef fish(pages 84–85), queen angelfish (page 85), but-terfly fish (page 85), and reef sharks (page 86).


3. Students should find the following informa-tion and record it in their notebooks:

■ Staghorn coral: is a type of hard coral;named for its familiar shape; thin mem-brane covers and protects hard coral’s sur-face; although made up of hard coral, thereef is very fragile, and pieces can break offeasily. (See Figure 3-19 on page 83.)

■ Spotted trunkfish: depends on camouflageto avoid being detected by predators; livesat the bottom of the reef, where it is diffi-cult to spot against the background of coraland speckled sand. (See Figure 3-22 on page84.)

■ Schooling reef fish: such as the grunt, gainprotection against predators by swimmingtogether in a group, or school, of their ownspecies. There is security in numbers; thechances of any fish being caught by apredator are reduced because of the largenumber in the school. (See Figure 3-23 onpage 85.)

■ Queen angelfish: very colorful, like manyother reef fish; its yellow and black colorsstand out in sharp contrast to the back-ground colors of the reef; the strong differ-ence between its own body colors, calledcolor contrast, enables fish of the samespecies to find one another in the maze oftunnels and crevices of the reef.

■ Butterfly fish: uses color to confuse preda-tors; has two fake eyespots at the base of itscaudal tail, which tricks predators intothinking that the back of the fish is itsfront; spots, bars, and stripes, whichobscure the outline of a fish are called dis-ruptive coloration. (See Figure 3-24 on page85.)

■ Reef sharks: large, predatory fish that patrolan area of the reef to protect its resourcesfrom competitors; such behavior by anorganism in defending its home area iscalled territoriality. (See Figure 3-25 on page86).


Have a student leader from each group read aloudthe information their group has obtained. Askanother student to write a brief summary abouteach of these reef organisms on the board. Havestudents copy the completed information intotheir notebooks.

Homework Assignment

Read pages 82–86. Answer Section Review ques-tions 1–3 on page 86. (See also Chapter Reviewpages 90–91 for additional homework questions.)

17

UNIT 2 KINGDOMS OF LIFE IN THE SEA

Chapter 4 /Unicellular Marine Organisms

INTRODUCTION

Chapter 4 introduces the student to classification, the branch of science important for making sense of thediversity of life on Earth. Also described are the “simple” life-forms that are so abundant on land and in the sea:bacteria and unicellular algae. Algae are crucial in their role as producers and, as such, form the base of vastoceanic food chains. Methods of nutrition in unicellular algae are discussed.

■ A scientific classification system helps scientists identify and understand the origins, adaptations, and relat-edness of organisms.

■ Bacteria play a crucial part in the functioning of the biological world, particularly in their role as decom-posers of organic matter.

■ Diatoms and dinoflagellates are important marine food producers. They also can cause harm to ocean lifewhen algal blooms occur.


Aim: How can we classify marine organisms?



1. Identify the five kingdoms of living things.

2. Describe organisms from each kingdom.

3. List the main characteristics of the organisms.


Show students a picture or model of the euglena.Ask them: Is it an animal or a plant? Explain.


1. The euglena has both animal-like and plant-like characteristics, and is classified in thekingdom Protista. The process of organizing

living things into groups based on similaritiesin structure is called classification. The Swedishbotanist Carolus Linnaeus (1707–1778) iscredited with being the founder of taxonomy,the science of classification.

2. WRITE THE AIM: How can we classify marineorganisms? Linnaeus classified living thingsinto the taxonomic groups kingdom (containsthe largest variety of related organisms), phy-lum, class, order, family, genus, and species.The species group consists of one kind oforganism. The modern classification systemrecognizes at least five kingdoms—monera,protista, fungi, plant, and animal.

3. KEY QUESTION: What kinds of organisms arefound in the different kingdoms? Organize theclass into five groups. Assign to each group adifferent kingdom. Have the students readabout their kingdom in the text (on pages 95–97). Distribute around the room various pic-tures, specimens, and/or models of differentmarine organisms from the five kingdoms.


Kingdom Organisms Characteristics

Monera Bacteria, cyanobacteria Single-celled; prokaryotes (lack a nuclear membrane); (blue-green algae) have a cell wall

Protista Algae, protozoa, seaweeds Mostly single-celled; eukaryotes (have a nuclear membrane)

Fungi Molds, yeasts Unicellular and multicellular eukaryotes; live off dead matter

Plantae Sea grasses, mangroves, cordgrass Multicellular; contain chlorophyll; have cell walls & vascular tissue

Animalia Vertebrates and invertebrates Multicellular; eukaryotic; lack cell walls; consume food; movement

Each student group should select the appro-priate organisms from their kingdom.

4. Copy onto the board the above table; leavethe “Characteristics” column blank. Have stu-dents from each group go to the board and fillin the information for their kingdom thatthey gathered from their observations andfrom their readings in the text.


Scientists use a classification system to study thefive major groups, or kingdoms, of living things.The ocean contains organisms from all five king-doms. Marine bacteria and algae play importantan part in ocean life, from producing (food-mak-ing) to breaking down (decomposing) organicmatter.

Homework Assignment

Read pages 93–97; answer Section Review ques-tions 1–3 on page 97. Then read pages 98–100.


Aim: How can we classify the unicellularalgae?



1. Classify the different types of unicellular algae.

2. Distinguish between diatoms and dinoflagel-lates.

3. Describe the significance of the unicellularalgae.


Tell the students to take a deep breath; then askthem to identify the source of most of the oxy-gen in the air that they breathe.


1. Microscopic, one-celled organisms that con-tain chlorophyll and live on or near the sur-face of the ocean produce most of the oxygenthat we breathe. These aquatic, plantlikeorganisms are called algae.

WRITE THE AIM: How can we classify marinealgae?

2. Have students look at the diatoms in Figure 4-4 (on page 103) and the dinoflagellates in Fig-ure 4-6 (on page 106). Draw on the chalkboardone representative diatom and one dinoflagel-late. One-celled organisms such as diatomsand dinoflagellates are classified in kingdomProtista. Diatoms and dinoflagellates float anddrift on or near the ocean surface; they arepart of the plankton population. Both kinds ofprotists have chlorophyll and carry out photo-synthesis.

3. KEY QUESTION: How can we distinguish betweendiatoms and dinoflagellates? Diatoms have atransparent cell wall composed of silica (whichlets in light for photosynthesis). The diatom’scell wall has two overlapping halves called

UNIT 2 / KINGDOMS OF LIFE IN THE SEA 19

frustules. (See Figure 4-5 on page 102.) Pointout that diatoms are classified according totheir shape. The round ones are called centricand the pen-shaped ones are called pinnate;and some diatoms form long chains.

4. Dinoflagellates have animal-like and plantlikecharacteristics. That means they can bothmake (because they have chlorophyll), andtake in, their food. Their cell walls are madeup of cellulose (like plants), not silica. Thedinoflagellates possess two microscopic hairscalled flagella, which are used for locomotion.


Diatoms and dinoflagellates are unicellularmarine algae that can make food by carrying outphotosynthesis and which produce much of theplanet’s oxygen as a result of this activity. Theirlife activities and unique characteristics have agreat impact on marine ecosystems.

Homework Assignment

Read pages 101–108. Answer Section Reviewquestions 1–3 on page 108.

Chapter 5 /Marine Algae and Plants

INTRODUCTION

In Chapter 5, students will learn that many different kinds of plants and plantlike algae live in and near theocean. The adaptive features that enable algae and plants to survive in a saltwater environment are explored.Also discussed are the ways in which marine plants and algae function as sources of food and shelter for marineanimals.

■ Hundreds of species of algae live in the sea, and a great variety of plants grow in and near the sea. Theseproducers have characteristics that help them carry out photosynthesis and survive in the salty, and some-times rough, conditions of an oceanic environment.

■ Marine algae and plants are important for the survival of animals in a variety of undersea and coastal marineenvironments. They also contribute to the “biological richness” of these environments.


Aim: How can we classify the multicellularalgae?



1. Classify the main kinds of multicellular algae.

2. Distinguish between the different types ofalgae.

3. Describe characteristics and habitats of thealgae.


Copy the following table onto the board; leaveblank except for the three groups of algae: red,brown, and green. Have students copy the tableinto their notebooks. During the activity, theywill fill in information about each phylum and itscharacteristics.


1. Show specimens or pictures of seaweeds. Mostof the algae that we read about and see are themulticellular algae, or seaweeds.


Algae Phylum Genus Name Characteristics and Habitat

Green Chlorophyta Ulva (sea lettuce) Thin, leafy, bright green; shallow water

Enteromorpha Filamentous, on rocks; intertidal zone

Codium Spongy, branching; subtidal zone

Acetabularia Umbrellalike; tropical waters

Brown Phaeophyta Laminaria (kelp) Long fronds, holdfast on rocks; subtidal zone

Sargassum Floats, branching, provides cover; open sea

Fucus (rockweed) Air bladders, branching, holdfast on rocks; intertidal zone

Red Rhodophyta Chondrus (Irish moss) Short, bushy, covers rocks; subtidal zone

Porphyra Thin leaves, attaches to rocks; intertidal zone

Corallina Hard, brittle, branching; intertidal zone

WRITE THE AIM: How can we classify the multi-cellular algae? Algae are classified within thekingdom Protista.

2. Organize the class into three groups—thegreens, the browns, and the reds—based onthe three different groups (phyla) of algae. Dis-tribute pictures and/or specimens of marinealgae around the room. Have students observethe specimens and use their textbooks (pages118–121 and 123–127) to get the informationthey need to fill in the table.

3. Call on a team leader from each group tomake a report to the class on their findings.Have a student fill in the table on the chalk-board for the class to copy into their note-books.


The multicellular algae are classified in three dif-ferent phyla based on the color of their pigments:brown, green, and red. Seaweeds are adapted tolive in a variety of marine habitats, from theintertidal and subtidal zones to the open ocean.

Homework Assignment



Aim: How are marine plants adapted to theirenvironment?



1. Classify the various marine plants.

2. Identify adaptations among the plants.

3. Describe habitats of marine plants.


Copy the table that is on the chalkboard intoyour notebook. Read pages 127–134.


1. Show students pictures or specimens of beachplants.

KEY QUESTION: What do these plants share incommon with one another? They have leaves forphotosynthesis, roots for absorbing water fromthe sand, and stems for transport. Becausebeach plants and ocean plants possess trueroots, stems, and leaves, they are called vascu-lar plants. Structures such as stems and leavesthat enable organisms to survive in their envi-ronment are called adaptations. The vascularplants are classified in the phylum Tracheo-phyta within the plant kingdom.


Common Name Genus Name Adaptations Habitat

Beach grass Ammophila Deep roots, underground stems Upper beach

Prickly pear cactus Opuntia Thick, waxy leaves Upper beach

Seaside goldenrod Solidago Stores water in stems Upper beach

Reed grass Phragmites Fluffy mass of brown flowers Upper beach

Cordgrass Spartina Salt glands in leaves Intertidal zone

Eel grass Zostera Grow close together in beds Subtidal zone

Turtle grass Thalassia Underground stems (rhizomes) Subtidal zone

Mangrove tree Rhizophora Prop roots Intertidal zone

2. WRITE THE AIM: How are marine plants adaptedto their environment? Organize the class intotwo groups. One group will cover the beachplants; the other group will cover the oceanplants. Distribute pictures and/or specimens ofmarine plants around the room. Have studentsobserve the specimens and use their textbooks(pages 127–134) to get the information theyneed to fill in the table.

3. Call on a team leader from each group tomake a report to the class on their findings.Have a student fill in the table on the chalk-board for the class to copy into their note-books.


Most marine plants are vascular plants. They pos-sess a variety of adaptations in their roots, stems,and leaves that enable them to live in diversehabitats, from the upper beach to the subtidalzone.

Homework Assignment

Read pages 127–134. Answer all Section Reviewquestions 1–3 on pages 129, 132, and 134. (Or:Answer Chapter Review questions 6–8 on page137 and 13–22 on pages 139–140.)


Chapter 6 /Simple Marine Animals

INTRODUCTION

Chapter 6 introduces the student to the world of protozoans and “simple” marine animals. The text explainshow they carry out their basic life functions, such as nutrition, sensitivity, and reproduction. The diversity andimportance of zooplankton species are discussed. The protozoans (found throughout the water column) aredescribed in detail, as are the sponges, rotifers, and bryozoans (i.e., the benthic animals).

■ A protozoan is a unicellular, animal-like organism.

■ An animal is a multicellular organism that consumes its food and is generally capable of movement.(Sponges and bryozoans are sessile.)

■ The zooplankton community is composed of protozoans and marine animals. Zooplankton are moved,mostly, by winds and currents.

■ The “simple” animals—sponges, rotifers, and bryozoans—are well-adapted to surviving the rigors of under-sea life. They show a variety of feeding methods (filter feeding, scavenging, active predation) and theyreproduce by various methods (including asexual and sexual means of reproduction).


Aim: How diverse are the marine zooplank-ton?



1. Distinguish between vertebrates and inverte-brates.

2. Identify temporary and permanent zooplank-ton.

3. Describe how plankton can be caught forstudy.


Have students observe pictures and/or specimensof a variety of vertebrates and invertebrates.

ASK THE CLASS: How are these organisms similarto one another? How are they different?


1. WRITE THE AIM: How diverse are the marinezooplankton? First define animals, then inver-

tebrates, and then zooplankton. Tell that mul-ticellular organisms that ingest food are clas-sified within the animal kingdom. The takingin of food by animals is called heterotrophicnutrition. The animal kingdom can be dividedinto two major subgroups, the vertebrates (ani-mals with backbones) and the invertebrates(animals without backbones).

2. KEY QUESTION: Where can you find an abun-dance of invertebrates? Many invertebrates arepart of the plankton population. Plankton aretiny organisms that float near the surface ofthe ocean. Animal and animal-like planktonare called zooplankton. Some species of zoo-plankton are unicellular organisms (protozoa);most others are small invertebrate animals.

3. Show students a plankton net, which is used tostrain zooplankton from the water. Zooplank-ton are subdivided into two groups: temporaryzooplankton and permanent zooplankton.The temporary zooplankton are the embryosor larvae of crabs, sponges, lobsters, clams, andother invertebrates. The permanent zooplank-ton are small invertebrate species, like cope-pods, which remain in the planktonpopulation throughout their entire life cycle.


4. KEY QUESTION: How can we compare the tem-porary and the permanent zooplankton? Draw acrab larva and a copepod on the board, or pro-ject on a screen, for students to copy into theirnotebooks. Also, refer students to Figures 6-1and 6-2 on page 147 in their text.

5. Organize the class into groups of three to fourstudents. Each group should prepare a briefsummary of the lesson. Have one studentfrom each group write the summary on theboard. Call on a student from each group toread their summary aloud.


The animal kingdom contains vertebrates andinvertebrates. In addition, there are the protozoa,which are tiny animal-like organisms. Some pro-tozoa and many marine invertebrates are foundin the ocean’s zooplankton population, whichconsists of temporary (invertebrate larvae) andpermanent (protozoan) zooplankton.

Homework Assignment

Read pages 141–148. Answer Section Reviewquestions 1–3 on page 149 (top).


Aim: How can we classify the protozoans?



1. Classify the various protozoans.

2. Identify their means of locomotion.

3. Describe how the protozoans move.


Show the class pictures or models of unicellularanimal-like organisms. Have students make a listof their observations.

ASK THE CLASS: What do all of these microor-ganisms have in common?


1. WRITE THE AIM: How can we classify the proto-zoans? All of these organisms are microscopic,one-celled animal-like organism called proto-zoans. Protozoans live in bottom sediments,on the surface of substrates, and within thewater column. Unicellular protozoans are clas-sified in the protist kingdom and to the phy-lum Protozoa. The protozoa are subdividedinto three different classes—ciliates, flagellates,and amebas—based on their means of loco-motion.

2. KEY QUESTION: How do the protozoa moveabout? Draw on the board, or project on anoverhead, a representative from each class ofprotozoans (ciliated, flagellated, and ameboid).List the following characteristics for eachgroup:

■ Ciliates: Move through the water by meansof the beating of their microscopic hairscalled cilia.

■ Flagellates: Contain two whiplike tailscalled flagella (singular, flagellum). Theactions of their flagella cause the organismto move in any direction.

■ Amebas: Live on the surface of substratesand move by means of a cytoplasmicstreaming (called amoeboid movement) intoextensions of their cell—the pseudopodia(“false feet”).


The protozoans are grouped into three differentclasses, based on their means of locomotion.These are: the ciliates, the flagellates, and theameboids. Protozoa include freshwater andmarine species.

Homework Assignment

Read pages 149–150 (top). Answer Section Reviewquestion 1 on page 55 (top).


Structure Function

Cilia Locomotion and food-getting

Mouth Ingestion (taking in of food)

Food vacuole Digestion (changing largemolecules into small ones)

Cytoplasm Transport (movement ofnutrients throughout the cell)

Nucleus Growth (increase in cell size) andreproduction (production ofmore cells)

Cell membrane Respiration (taking in O2, givingoff CO2)

Contractile vacuole Excretion (elimination of cellularwaste)

Stalk Sensitivity (contraction of stalk inresponse to external stimulus)


Aim: How does a unicellular organism carryout its life functions?



1. Identify structures in the Vorticella.

2. Define the basic life functions of all organisms.

3. Explain how the Vorticella carries out its func-tions.


Have the students make a list of the basic lifefunctions of living things.


1. Life functions are the activities that are neces-sary for an organism to carry out in order tosurvive. The life functions include ingestion,digestion, growth, transport, excretion, respi-ration, locomotion, reproduction, and sensi-tivity.

WRITE THE AIM: How does a unicellular organ-ism carry out its life functions? The Vorticella, aone-celled animal-like protozoan, carries outall its life functions within its single cell. TheVorticella is easier to observe than other proto-zoans because it is attached to a substrate.Mention that organisms that live attached to asubstrate are called sessile.

2. Use a wall chart, drawing, or projection of theVorticella on the board for the students to copyinto their notebooks. Draw two columns onthe board, labeled Structure and Function.

ASK KEY QUESTIONS: (e.g., How does the Vorti-cella ingest its food?) to introduce and discusseach life function. Point out each structure asyou discuss its function, and elicit studentresponse as you fill in both columns with theappropriate information.


The Vorticella is a unicellular, ciliated aquatic pro-tozoan that carries out all its life functions (whichare like those of multicellular organisms) withinits single cell.

Homework Assignment

Read pages 150–154. Answer Section Reviewquestions 2 and 3 on page 155 (top).


Aim: How is the sponge adapted to its envi-ronment?



1. Explain why the sponge is considered “sim-ple.”

2. Describe the structure of a typical sponge.

3. Identify the classification of the sponge.


Structure Function

Ostia (small pores) Ingestion (taking in of food andwater)

Osculum (large pores) Excretion (elimination of cellularwastes)

Collar cells Digestion (changing large (have flagella) molecules into small ones); filter

feeding (movement of flagellacause currents of water to enterand leave the sponge)

Ectoderm and Respiration (taking in O2, giving endodermoff CO2)

Spicules Providing structure andprotection


Pass a few (natural marine) sponges around theclassroom. Have students make three observa-tions about the structure of a sponge. Then givethe classification of the sponge (i.e., phylumPorifera).


1. List on the board some of the student obser-vations on sponge structure, which mayinclude the following: (a) the sponge hasmany holes; (b) the sponge is elastic; (c) allparts of the sponge look alike; and (d) theadult sponge does not move (i.e., it is sessile).

WRITE THE AIM: How is the sponge adapted toits environment?

2. Use a wall chart, drawing, or projection of asponge on the board for the students to copyinto their notebooks. Draw two columns onthe board, labeled Structure and Function. Askkey questions (e.g., How does the sponge ingestits food?) to introduce and discuss each lifefunction. Point out each structure as you dis-cuss its function, and elicit student responseas you fill in both columns with the appropri-ate information.

3. KEY QUESTION: Why is the sponge considered tobe a simple organism? The sponge is a simpleanimal (even though it is multicellular)

because it has only two cell layers—an innerlayer (the endoderm) and an outer layer (theectoderm)—and it lacks (cellular) specialization.


The sponge is a simple pore-bearing, filter-feed-ing, multicellular organism that is composed oftwo layers of (mostly unspecialized) cells. Thesponge is classified in phylum Porifera (“pore-bearing”).

Homework Assignment

Read pages 155–157. Answer Section Reviewquestion 1 on page 164, and Chapter Reviewquestions 6 on page 166 and 13–23 on page 168.

LESSON 5 (pages 157–161 top)

Aim: What do we know about the life cycleof the sponge?



1. Describe the life cycle of the sponge.

2. Identify the stages in a sponge’s development.

3. Explain how an adult sponge encrusts on asubstrate.


ASK THE CLASS: How does the (adult) sponge attachto a substrate if it cannot swim?


1. The adult sponge has no locomotion, but dur-ing its early development it lives as a swim-ming larva (embryo) within the planktonpopulation. The period of time from earlydevelopment and growth through maturity inan organism is called its life cycle.


2. WRITE THE AIM: What do we know about thelife cycle of the sponge? The life cycle beginswith reproduction, the activity by which organ-isms produce offspring. Sponges may eitherhave separate sexes or may have both maleand female sex cells within the same sponge.Draw a zygote on the board, and show theclass an adult sponge.

KEY QUESTION: How does a multicellular spongedevelop from a single cell?

3. Show the class pictures or models of each stageof sponge development, or have students referto Figure 6-6, on page 157, in their textbooks.The rapid division of the fertilized egg cell, orzygote, is called cleavage. The organism duringearly stages of cellular development is calledan embryo. When the embryo is a solid ball ofcells it is in the morula stage. When it is a hol-low ball of cells, it is in the blastula stage.

4. KEY QUESTION: How and when does the embryobecome a swimmer? When the cells of a blastuladevelop whiplike flagella, the sponge embryois able to swim. The swimming embryo iscalled a larva. When the larva attaches to asubstrate, it develops into an adult sponge.The mature sponges release the gametes intothe water. Fertilization and development areexternal.


The sponge’s life cycle begins with the productionof offspring. A sponge develops from a single, fer-tilized egg cell that goes through various stages ofembryonic development. It becomes a free-swim-ming larva, which then settles onto a substrateand develops into a sessile adult sponge.

Homework Assignment

Read pages 157–161 (top). Answer Section Reviewquestion 2 on page 164, and Chapter Reviewquestion 7 on page 166.


Aim: How do simple, multicellular organ-isms carry out their life functions?



1. Identify a bryozoan and a rotifer.

2. Describe how they carry out their life func-tions.

3. Explain how they are adapted to their envi-ronment.


Use an overhead projector to show the class arotifer and a bryozoan. Have the students try toidentify these organisms (i.e., what type of life-form each might be).


1. The rotifer and the bryozoan are multicellular,microscopic marine organisms that are classi-fied in two different phyla. The rotifer is inphylum Rotifera and the bryozoan is in phy-lum Bryozoa.

2. Write the Aim: How do simple, multicellularorganisms carry out their life functions? Organizethe class into six groups to do research onrotifers and bryozoans (on pages 161–164).Assign to each of five groups one of the fol-lowing life functions: locomotion, ingestion,digestion, respiration, and reproduction.Assign “habitats” to the sixth group. Draw twocolumns on the board, labeled Rotifer Structureand Rotifer Function. Ask the team leader fromeach group to fill in the columns on the boardwith the appropriate information aboutrotifers. All students should copy the com-pleted tables into their notebooks.

3. KEY QUESTION: How would you describe thehabitat of the rotifer? Have the team leader from


Rotifer Structure Rotifer Function

Cilia Locomotion (moving from place to place)


Stomach, intestine, anus Digestion (changing large molecules into small ones); one-way digestive system

Cell membrane Respiration (taking in O2, giving off CO2)

Separate sexes: ovary (egg cells) Sexual reproduction (external fertilization); asexual parthenogenesis may also occurand testes (sperm cells)

Bryozoan Structure Bryozoan Function


Stomach, intestine, anus Digestion (changing large molecules into small ones); one-way digestive system

Cell membrane Respiration (taking in O2, giving off CO2)

Hermaphrodite (both ovaries and Sexual reproduction (self-fertilization may occur); Asexual reproduction testes in same individual); Budding (budding); a small part breaks off from the parent bryozoan to become a new also occurs. organism.

group 6 provide the appropriate information.Rotifers live in the moist sands along the shoreand in the gravel of aquarium tanks. Theyswim by means of cilia and they can telescopetheir bodies to facilitate movement. Somerotifers are predators, while others scavengeon debris.

4. Draw two more columns on the board, labeledBryozoan Structure and Bryozoan Function. Askthe team leader from each group to fill in thecolumns on the board with the appropriateinformation about bryozoans. All studentsshould copy the completed tables into theirnotebooks.

5. KEY QUESTION: What do we know about thehabitat of the bryozoan? Have the team leaderfrom group 6 provide the appropriate infor-mation. Branching colonies of bryozoans com-

posed of hundreds of individuals cover thesurfaces of rocks, seaweeds, and shells. Somespecies of bryozoans encrust on substrates,while other bryozoan colonies stand erect.


The rotifer and the bryozoan are examples ofmicroscopic, multicellular animals that live inmarine sediments and on the surfaces of sub-strates.

Homework Assignment

Read pages 161–164. Answer Section Reviewquestion 3 on page 164, and Chapter Reviewquestion 8 on page 166.

28

UNIT 3 MARINE INVERTEBRATES

Chapter 7 /Cnidarians

INTRODUCTION

In Chapter 7, students will learn about cnidarians, the marine animals that have stinging tentacles. At firstglance, animals such as anemones, corals, and jellyfish look very different, but they have similar body structuresand functions. Students will learn about feeding and reproduction in cnidarians. The polyp and the medusa arethe basic body plans found in this phylum. Some cnidarians are colonial; in these species, many differentpolyps function together as a single organism.

■ All cnidarians have stinging tentacles, some of which contain toxins.

■ All cnidarians have a nerve net (simple nervous system) and exhibit radial symmetry (in both the polypand the medusa phase).

■ Some cnidarians, e.g., corals, have symbiotic algae living within them.


Aim: How does the jellyfish carry out its lifefunctions?



1. Describe the structure of the jellyfish.

2. Explain how the jellyfish carries out its lifefunctions.

3. Compare and contrast different types of jelly-fish.


Show examples or models of corals, seaanemones, and jellyfish to the class. Compareand contrast these organisms.


1. The coral, sea anemone, and jellyfish are allanimals with stinging tentacles. These inver-tebrates are classified in phylum Cnidaria. Thejellyfish belong to class Scyphozoa.

WRITE THE AIM: How does the jellyfish carry outits life functions? Have students look at thephotographs of a moon jelly (Aurelia), Figure7-2 on page 174, and of a lion’s mane jellyfish(Cyanea), on page 177 (or use an overhead pro-jector to show the class these images). Remindstudents that “jellyfish” are not fish at all, butare invertebrate animals in their own class.

2. KEY QUESTION: How does the jellyfish float andmove? Draw a diagram on the board based onFigure 7-1 on page 173. The umbrella-shapedstructure is called the medusa. The medusa iscomposed of two membranes, with a jellylikemass called the mesoglea between them. Theshape of the medusa, and its thinness and lowdensity, enable the jellyfish to float. The

UNIT 3 / MARINE INVERTEBRATES 29

medusa contracts in a rhythmic fashion,which causes these animals to pulsate gentlythrough the water. Because they float along,jellyfish are considered part of the planktonpopulation.

3. KEY QUESTIONS: How does the jellyfish obtainand digest food? Their long transparent tenta-cles contain stinging cells, called cnidoblasts.Inside each cnidoblast there is a coiled threadwith a barb at the end, called a nematocyst.Refer students to Figure 7-3 on page 174. Thebarb is coated with a paralyzing toxin that canimmobilize small prey. Contracting tentaclesbring the prey up to the mouth. Food isingested through the mouth and digested in asaclike digestive cavity. Digestion in the jelly-fish is extracellular and occurs in a two-waydigestive tract, since waste products are elimi-nated through the mouth. The jellyfish canalso catch food with its medusa, the undersideof which has a sticky mucus membrane thatcatches plankton.

4. KEY QUESTIONS: How does the jellyfish breathe?Since the jellyfish has thin membranes, oxygencan diffuse directly from the water into its bodycells. The cellular waste product, carbon diox-ide, diffuses in the opposite direction, from thecells into the water. This gas exchange occursover the entire surface of the jellyfish.

5. KEY QUESTION: How does the jellyfish repro-duce? The jellyfish have separate sexes. Theovaries and testes form a four-leaf-clover pat-tern, visible at the top of the medusa. Thetestes produce sperm cells, which swim out ofthe male’s mouth and into the female’s mouthand digestive sac. The sperm cells fertilize theegg cells in the ovary, producing embryos thatpass through various developmental stages(see Figure 7-4 on page 176).

6. KEY QUESTION: What have you learned from thestudy of the jellyfish? Organize the class intofive groups and assign one life function toeach group (ingestion, food-getting, respira-tion, locomotion, and reproduction). Haveeach group prepare a summary from the infor-

mation in their notes. Have the team leaderfrom each group read the summary aloud inclass.


The jellyfish is an invertebrate with stinging ten-tacles that floats near the surface of the ocean,where it feeds on plankton and other small ani-mals. Like all cnidarians, it has radial symmetry.

Homework Assignment

Read pages 171–178 (top). Answer Section Reviewquestions 1–3 on page 178, and Chapter Reviewquestions 9–11 on page 190.

LESSON 2 (pages 178–180 top; 184–186)

Aim: How are sea anemones and hydroidsadapted to their environment?



1. Compare and contrast sea anemones andhydroids.

2. Explain how sea anemones carry out their lifefunctions.

3. Describe different adaptive features of thehydroids.


Show the class a photograph of a sea anemone,an Obelia, and a Physalia. Have students compareand contrast their observable features with thoseof a jellyfish.


1. The sea anemone is an animal with stingingtentacles that (superficially) looks like anupside-down jellyfish. But it is more closely


related to the corals and is placed in classAnthozoa. The mound of tissue that forms themain body of a sea anemone is the polyp.

2. WRITE THE AIM: How are the sea anemones andhydroids adapted to their environment? Organizethe class into several groups of two to four stu-dents each. Half the groups will be the SeaAnemones and the other half will be theHydroids. Have the Sea Anemones read Section7.2 and copy Figure 7-6 (page 178) into theirnotebooks. Have the Hydroids read Section 7.4and copy Figures 7-10 (page 185) and 7-11(page 186) into their notebooks.

3. Draw two columns on the board, labeled SeaAnemone Structure and Function and HydroidStructure and Function. Ask a team leader fromeach type of group to fill in the columns onthe board with the appropriate information.For sea anemones, the following should beincluded: mouth/ingestion; epidermis/respira-tion; tentacles/food-getting; digestive cavity/digestion; muscular foot/attachment to sub-strate. For hydroids, the following should beincluded: mouth/ingestion; tentacles/food-get-ting; and float/locomotion (to aid sailing) orstalk/sessile (attachment to substrate). All stu-dents should copy the completed tables intotheir notebooks.

4. KEY QUESTION: How can we compare andcontrast the sea anemone and the hydroid? Thesea anemone and the hydroid are both cnidar-ians; they both have stinging tentacles andradial symmetry. The sea anemone is a solitaryanimal. Most hydroids, such as Obelia andPhysalia (Portuguese man-of-war) are colonialanimals, because they are made up of groupsof specialized polyps joined together (on astalk in Obelia; under a single float in Physalia).The colonial cnidarians are placed in classHydrozoa. The dominant structure in the seaanemone is the polyp; it lives attached to asubstrate in the intertidal and/or subtidalzones. Some hydroids, like Obelia, live attachedto a substrate; others, like Physalia, float anddrift on the ocean surface. Sea anemones canreproduce sexually and/or asexually. Hydroids

contain reproductive polyps; in Obelia, thesepolyps form a brief medusa (sexual) phase.


The cnidarians, such as sea anemones andhydroids, are adapted to their environment bypossessing stinging tentacles for food-getting. Thesolitary sea anemone has a muscular foot foranchorage to substrates. The colonial Physalia hasa gas-filled float to aid in locomotion.

Homework Assignment

Read pages 178–180 (top) and 184–186. AnswerSection Review questions 1–3 on page 180 and 1–3 on page 186.


Aim: How does the coral carry out its lifefunctions?



1. Explain how the coral animal builds a reef.

2. Identify the different kinds of coral.

3. Describe the structure of a coral polyp.


Display specimens or photographs of hard coralsand soft corals in front of the class. Have studentssketch and label them in their notebooks.


1. The coral is a tiny animal with stinging tenta-cles. Corals often resemble familiar objects, sothey have names such as brain coral, staghorn


coral, sea fan, and sea whip. Corals are dividedinto two types—hard corals and soft corals—both of which (along with the sea anemones)belong to class Anthozoa. The hard corals havean outer covering of limestone, which cangrow into a massive stony structure called acoral reef.

2. WRITE THE AIM: How does the coral carry out itslife functions? The basic structure of the coralanimal is the coral polyp. Draw on the board,or project on an overhead, a picture of thecoral polyp. (Refer to Figure 7-8 on page 182.)In hard corals, the polyp sits in a cuplikedepression on the surface of a reef. The stonydepression is composed of the compound cal-cium carbonate, or limestone, which is pro-duced by the polyps that live on the surface.

3. KEY QUESTION: How does a coral polyp get theenergy it needs to build a reef? Specialized cellsthat live within the polyp, called zooxanthel-lae, provide some of the energy needed toextract calcium from the seawater and use itto construct the limestone skeleton. The zoox-anthellae are unicellular algae, which are cap-tured by the coral polyp from the surrounding

seawater. The chloroplasts in the zooxanthel-lae carry out photosynthesis and produceenergy-rich glucose.

4. KEY QUESTION: What conditions are needed forcorals to grow? Coral reefs need warm, clean,shallow tropical oceans where the water isclear and receives abundant sunlight.


The coral is a tiny animal that has stinging ten-tacles. Its basic unit of structure is the coral polyp,which contains symbiotic algae. Over time, mil-lions of coral polyps living together form a reefby secreting cup-shaped limestone depressions inwhich each polyp sits.

Homework Assignment

Read pages 180–184 (top). Answer Section Reviewquestions 1–3 on page 184, and Chapter Reviewquestions 7 on page 189 and 12–24 on pages190–192.

Chapter 8 /Marine Worms

INTRODUCTION

The world of marine worms is explored in Chapter 8. Students will learn about the digestive and reproductivesystems of marine worms and about their roles in the marine environment. Although marine worms tend toresemble one another in their general shape, this group is actually composed of many different types of organ-isms, with different levels of structural development and complexity. Worms vary in size from microscopic tomany meters long, are all bilaterally symmetrical, and are found throughout the water column.

■ There are flatworms, roundworms, and segmented worms. Worms are the first organisms to exhibit bilat-eral symmetry.

■ Worms are found throughout the marine environment, from the ocean surface to intertidal sediments tothe deep seafloor.

■ Marine worms exhibit a variety of lifestyles: some are parasitic, some free-living; some filter feed, some arepredatory; and some live in tubes, which they construct of proteins and minerals.


Sexual

(hermaphrodite);

external fertilization

Ocean surface; hunts

copepods, fish eggs,

& fish larvae

One-wayFew cm long; has tiny

fins for swimming

Arrow Worm: Phylum

Chaetognatha

(not discussed in text)Hydrothermal vents;

rely on compounds

from chemosynthetic

symbiotic bacteria

Gutless1 meter long; tube-

dwelling

Giant Tube Worm:

Phylum Pogonophora

Sexual (separate sexes)

(Note: Earthworm, also

an annelid, is a

hermaphrodite)

Intertidal & subtidal

zones (in sediments);

eats organic debris

& tiny invertebrates

One-way tract

(with fluid-filled

coelom

Segmented; small (but

not microscopic)

Sandworm: Phylum

Annelida

Sexual (usually separate

sexes); internal

fertilization

Intertidal zone (in

sediments); eats

organic debris

One-way tractRound; tapered at ends;

up to 1 meter long

Roundworm: Phylum

Nematoda

Asexual (regenerate)

& sexual; external

fertilization

Intertidal zone (in

sand & water); eats

small fish & worms

One-way tractFlat; usually 1 meter,

up to 12 meters long

Ribbon Worm: Phylum

Nemertea

Asexual (regenerate) &

sexual (hermaphrodite);

internal fertilization

Aquatic; eats micro-

organisms & organic

debris along bottom

Two-way tractFlat; tiny to very large

species

Planarian: Phylum

Platyhelminthes

ReproductionHabitat & FeedingDigestionBody TraitsWorm

LESSON 1 (pages 194–198, 200–205)

Aim: What is known about marine worms?



1. Explain why worms are classified in differentphyla.

2. Describe characteristics of the different wormphyla.

3. Discuss similarities and differences among theworms.


Have students copy into their notebooks the firstcolumn and the four category headings from thefollowing table, which profiles six major phyla ofmarine worms.


1. Worms resemble one another in generalshape. The body is longer than it is wide. Sinceworms are not a single taxonomic group, theyare classified into several phyla.

2. WRITE THE AIM: What is known about marineworms? Organize the class into six groups,with each team researching a different marineworm. Information on the worms can befound on the following pages: planarian(195–196), ribbon worm (197), roundworm(198), sandworm (200–202), giant tube worm(203–204), and arrow worm (204–205). Havestudents sketch their worm and describe itstraits.

3. Send a student from each group to the boardto read their findings aloud and to fill in theinformation. All students should copy thecompleted table into their notebooks.


4. Some important facts about the marine wormsthat may be overlooked by the students, butthat you may want to mention, are:

■ Planaria: flattened bodies; some are micro-scopic, others are macroscopic; has a ven-tral mouth, branched digestive cavity,two-way digestive tract, and two eye spots.

■ Ribbon worm: largest worm in the ocean;averages one meter in length; inhabits theintertidal zone; burrows in the sand orswims gently; can break into many smallpieces and regenerate; also has sexualreproduction.

■ Sandworm: segmented body, with paddle-like appendages called parapodia; burrowsin marine sediments in intertidal and sub-tidal zones; captures prey with two sharphooks in mouth; breathes through thin,moist skin; has ventral nerve cord andbrain; closed circulatory system; is her-maphroditic; excretes wastes throughnephridia.

■ Giant tube worm: lives near deep-seahydrothermal vents; up to one meter in

length; utilize energy from chemosyntheticbacteria that live inside them.

■ Roundworm: rounded body with taperedends; most numerous of all worms; lives inmoist sediments in intertidal zone; movesby whipping action of body; feeds onorganic debris.

■ Arrow worm: tiny and transparent; has tinyfins; active swimmer; also floats with plank-ton; uses modified mouth bristles (hooks)to prey on plankton; has two eyes.


There are enough structural difference among theworms to justify their being classified into sepa-rate phyla. Worms are an important part of allmarine ecosystems, from the ocean surface to thedeep seafloor.

Homework Assignment

Read pages 193–198 and 200–205. Answer Chap-ter Review questions 13–25 on pages 210–212.

Chapter 9 /Mollusks

INTRODUCTION

The soft-bodied invertebrates discussed in this chapter are the mollusks, an extremely diversified phylum ofaquatic animals. Students will learn about the important characteristics and life functions of the bivalves, gas-tropods, and cephalopods (and two other “lesser” mollusk groups). The distinguishing feature of this group isthe external shell, although this has been lost in most cephalopods. Glands in the mantle secrete the mol-lusk’s shell.

■ Bivalves, e.g., the clam, are distinguished by having two shells, or valves.

■ Gastropods, e.g., the snail, have one (usually coiled) shell.

■ Cephalopods, such as the octopus, have lost the external shell; they are characterized by having a promi-nent head and long tentacles.

■ Mollusks are found throughout the marine environment; they exhibit a variety of feeding methods, from fil-ter feeding to grazing to hunting. Some mollusks live attached to a substrate; others are motile.


Structure Function

Shell (Exoskeleton) Protection

Adductor muscles Contraction

Incurrent siphon Water and food intake

Excurrent siphon Waste removal

Gills Breathing (gas exchange)

Mouth, stomach, intestines, Digestion (one-way)anus

Kidney Excretion

Heart Transport (open system)


Aim: How does a bivalve carry out its lifefunctions?



1. Describe how the clam is classified.

2. Identify the main structures in a clam.

3. Discuss the life functions of a clam.


Distribute some clamshells for the class toobserve. Have all students make a sketch of aclamshell in their notebooks.


1. The snail, oyster, clam, and mussel all have ashell, or exoskeleton, that protects the soft-bod-ied animal inside. These soft-bodied animalsare called mollusks and are classified in phylumMollusca.

2. WRITE THE AIM: How does a bivalve carry outits life functions? Display the clamshells. Men-tion that mollusks with two shells are calledbivalves and belong to class Bivalvia (or Pelyce-poda). Clamshells are hinged at one end, andare kept closed by short, tough adductor mus-cles. Point out the muscle attachment areasinside the shell. The outside of the shell haslines on it. Explain that each line is a newlayer of shell that the clam produces as itgrows. The lines form bands, and each bandrepresents a year’s growth.

3. KEY QUESTION: What do we know about theinternal anatomy of the clam? Use a wall chart,drawing, or projection of the clam’s internalanatomy for the students to copy into theirnotebooks. (You can also direct students toFigure 9-17 on page 230.) Draw two columnson the board, labeled Structure and Function.Ask key questions (e.g., How does the clam

ingest food? and How does the clam breathe?) tointroduce and discuss each life function. Pointout each structure as you discuss its function,and elicit student response as you fill in bothcolumns with the appropriate information.Have students copy the completed chart intotheir notebooks.


Bivalves such as the clam are soft-bodied animalsthat possess an exoskeleton (shell) to protect theinternal organs, which carry out their life func-tions. Most (but not all) marine mollusks have anouter shell to protect their soft bodies.

Homework Assignment

Read pages 213–218. Answer Section Reviewquestions 1–3 on page 218, and Chapter Reviewquestion 6 on page 232.


Aim: How does a gastropod carry out its lifefunctions?



1. Describe how the snail is classified.


Structure Function

Shell Protection

Muscular foot Locomotive

Anterior antennae (eyes) Vision

Posterior Antennae Sensitivity

Siphon Water intake

Gills Breathing

Radula Ingestion

Mouth, stomach, intestines, Digestion (one-way)anus

Kidney Excretion

Heart Transport (open system)

2. Identify structures in the snail.

3. Discuss the life functions in the snail.


Distribute some snail shells (uninhabited!) for theclass to observe. Have all students make a sketchof a snail shell in their notebooks.


1. The snail is a type of mollusk that possesses asingle shell, so they are commonly called uni-valves (“one shell”). Snails are placed in classGastropoda and are also known simply as gas-tropods (“stomach-foot”).

2. WRITE THE AIM: How does a univalve carry outits life functions? Use a wall chart, drawing, orprojection of the snail’s internal anatomy forthe students to copy into their notebooks.(You can also direct students to Figure 9-8 onpage 219.) Draw two columns on the board,labeled Structure and Function. Ask key ques-tions (e.g., How does the snail move? and Howdoes the snail ingest food?) to introduce and dis-cuss each life function. Point out each struc-ture as you discuss its function, and elicitstudent response as you fill in both columnswith the appropriate information. Have stu-

dents copy the completed chart into theirnotebooks.


Gastropods such as the marine snail are soft-bodied mollusks that posses a univalve exoskele-ton to protect their internal organs, which carryout all life functions. They use a toothed mouth-part called a radula to eat either algae or (living ordead) animal matter.

Homework Assignment



Aim: How diverse are the mollusks?



1. Identify the different classes of mollusks.

2. Describe the characteristics of each class.

3. Discuss diversity among the mollusks.


Distribute a variety of mollusks (specimens, mod-els, or pictures) for students to observe. Have stu-dents make a list of similarities and differences.


1. There are more than 100,000 different speciesof mollusks, which are placed into differentclasses based on the structural differencesamong them.

2. WRITE THE AIM: How diverse are the mollusks?Organize the class into six groups, with eachteam researching a different mollusk. Infor-mation on the specific mollusks can be found


on the following pages: mussel (215–216),abalone (222), sea slug (223), squid (224, 226,228), octopus (224, 226–227, 228), and chiton(229). Have students draw their mollusk anddescribe its characteristics.

3. Send a student from each group to the boardto read their findings aloud and to write downsome key facts about their mollusk. All stu-dents should copy the information into theirnotebooks.

4. Some important facts about the mollusks thatyou may want to see mentioned are:

■ Mussel (genus Mytilus, class Bivalvia): con-tains microscopic hairs called cilia, whichbeat back and forth, causing currents ofwater to enter and leave the mussel;secretes byssal threads, which enable it toattach firmly to substrates; has membrane,called the mantle, which secretes and linesthe insides of both shells.

■ Abalone (genus Haliotis, class Gastropoda):largest of the flat-shelled gastropods; inhab-its the rocky Pacific Coast where it grazeson algae on the rocks; mantle secretes ashiny, iridescent material (mother-of-pearl),which lines the insides of its shells.

■ Sea Slug (genus Dendronotus, class Gas-tropoda): also called a nudibranch, it is asnail without a shell; glides along seafloorin intertidal and subtidal zones, grazing onalgae; sea hares (a type of nudibranch)grow up to 75 cm in length and weigh 16kg (biggest marine gastropod).

■ Squid (genus Loligo, class Cephalopoda):swims in schools by means of a kind of jetpropulsion; water is drawn into the mantle

cavity and expelled through the siphon,causing squid to be propelled in the oppo-site direction; has ten tentacles; uses suc-tion disks on tentacles to capture and graspprey; releases ink cloud to avoid predators.

■ Octopus (genus Octopus, class Cephalopda):solitary animal; lives in crevices and underrocks on the seafloor; has eight tentacles,with suction disks to grasp prey; pigmentedcells in its skin (chromatophores) expandand contract to change its skin color andpattern (for camouflage); releases ink cloudto avoid predators; intelligent.

■ Chiton (class Polyplacophora): has overlap-ping shells, a characteristic not found inany other mollusk (hence its own class); noeyes or tentacles; inhabits rocky intertidalzones around the world; uses its muscularfoot to glide over rocks, where it scrapes offand grazes on algae with its radula.


The mollusks are a diverse group of invertebratesthat are placed into several different classes. Themembers of each class share common structuralcharacteristics yet show a variety of adaptationsto the marine environment.

Homework Assignment

Read pages 224–229. Answer Section Reviewquestions 1–3 on page 228 and 1–3 on page 229,and Chapter Review question 8 on page 232. (Seealso Chapter Review pages 233–235 for additionalhomework questions.)

Chapter 10/Crustaceans

INTRODUCTION

The invertebrates that are discussed in Chapter 10 are the marine crustaceans, in particular, and the arthro-pods, in general. These “armored” animals are characterized by having a tough exoskeleton and numerous


jointed appendages. There is great diversity among the arthropods. The crustaceans, which includes lobsters,crabs, shrimp, copepods, barnacles, and the like, are found throughout the world’s oceans and constitute animportant food source for many marine animals. Students will learn about marine arthropods’ structures andunique adaptations.

■ All arthropods have an exoskeleton and jointed appendages. The protective exoskeleton is composed ofchitin, a type of carbohydrate.

■ Crustaceans have bilateral symmetry and two main body segments (the cephalothorax and the abdomen).They have five or more pairs of appendages-—some for food-getting, some for movement.

■ Some crustaceans filter feed, some scavenge, and many are predatory.

■ Tiny crustaceans, such as copepods and krill, form the basis of oceanic food chains.


Aim: How are the arthropods adapted totheir environment?



1. Explain how arthropods are adapted to theenvironment.

2. Describe how the lobster carries out its lifefunctions.

3. Discuss body structures and functions in thelobster.


Display pictures or models of arthropods.Describe some common characteristics.


1. Arthropods, such as the lobster, barnacle, andhorseshoe crab, have several pairs of movablearms and legs, called jointed appendages. Theyalso possess an exoskeleton, composed of atough, fibrous material called chitin, whichimparts strength and flexibility to the skeleton.These invertebrates are all classified within thephylum Arthropoda (meaning “jointed feet”).

2. WRITE THE AIM: How are the arthropodsadapted to their environment? Show a wall chart,

drawing, or model of a lobster (to serve asyour representative arthropod) for the class toobserve. Arthropods (like the lobster) that pos-sess separate head (cephalo), chest (thorax), andabdominal regions, and which have five pairsof legs, belong to class Crustacea.

3. KEY QUESTION: How does the external anatomyof a lobster adapt it to its environment? Refer stu-dents to Figure 10-2 on page 239, whichshows the external and internal anatomy of alobster. The first pair of legs is called the che-lipeds. These two claws are used for seizingfood, while the other four pairs are the walk-ing legs. The exoskeleton that covers the headand chest is called the carapace. The head con-tains the eyes, antennae, and mouthparts usedfor feeding. The thorax contains appendagesused for food-getting and the walking legs.Crustaceans also swim, using their paddlelikeswimmerettes, which are located in theabdomen.

4. KEY QUESTION: How can the lobster grow if it is enclosed in a rigid exoskeleton? The crus-taceans can shed their outer covering once ormore each year, a process called molting. Crus-taceans can also regenerate body parts. If anappendage (such as a claw) is lost in a fight,another one will grow back in its place.

5. KEY QUESTION: How does the lobster carry outits life functions? Lobsters, like most crus-taceans, are largely scavengers. Food is digestedin a one-way digestive tract consisting of amouth, esophagus, stomach, and intestine.


The rapid beating of the mouthparts sends cur-rents of water over the gills (located under thecarapace). Oxygen and nutrients are trans-ported throughout the body by the blood, inan open circulatory system. The blood is blue,due to the presence of a copper-based pigment,hemocyanin. The nervous system includes aventral nerve cord. Reproduction is sexual; fer-tilization and development are external.


Arthropods are a very successful phylum, com-prising over a million species. The special adapta-tions of arthropods (and crustaceans in particular)include: several pairs of jointed appendages (forfeeding, fighting, and locomotion); a toughexoskeleton that protects the internal organs; andthe ability to shed and re-grow the exoskeleton,as the body grows.

Homework Assignment

Read pages 236–240 (top). Answer Section Reviewquestions 1–3 on page 240.


Aim: How are crustaceans adapted to theirmarine environment?

Instructional Objective


1. Describe physical and behavioral adaptationsof crustaceans.

2. Identify crustaceans that live in marine envi-ronments.

3. Explain how crustaceans carry out their lifefunctions.


Display specimens or pictures of crustaceans suchas the crab, shrimp, copepod, and barnacle. Have

students observe and list some features these ani-mals have in common.


1. Point out that all of the specimens, which arecrustaceans, have bilateral symmetry and arecomposed of three body segments: the head,thorax, and abdomen.

WRITE THE AIM: How are crustaceans adaptedto their marine environment?

2. Organize the class into five groups, with eachteam researching a different crustacean. Infor-mation on the crustaceans can be found onthe following pages: mole crab (241), fiddlercrab (240–241), mantis shrimp (244), copepod(244), and barnacle (247, 249).

3. Have the students draw their crustacean anddescribe its characteristics. Send a studentfrom each group to the board to read theirfindings and to write down some key factsabout their crustacean. All students shouldcopy the information into their notebooks.

4. Some important facts about crustaceans thatyou may want to have students mention:

■ Mole crab (genus Emertia): lives in the tur-bulent surf zone; has a smooth, stream-lined body to deflect waves; uses paddlelikeappendages for moving through sand andwater; uses featherlike antennae to capturemicroscopic organisms between the sandgrains.

■ Fiddler crab (genus Uca): digs tunnels in thesand along bays and inlets; leaves tunnelsat low tide to search for food; is named forits large claw (only in males), which is usedto threaten or fight with other males overterritory.

■ Mantis shrimp (genus Squilla): the largestshrimp, it grows up to 25 cm in length;burrows in the sand, from where it spearsprey such as worms and small fish with itsspiny front appendages; found (in Atlantic)from Cape Cod to Brazil.

■ Copecod (genus Calanus): found floatingand drifting on the ocean surface in tem-


perate zones; less than half a cm in length;eats mainly diatoms and is part of theplankton population; can be caught (forstudy) in a plankton net during spring andsummer.

■ Barnacle (genus Balanus): has overlappingsharp plates enclosing it; lives in the inter-tidal zone, glued to rocks and other hardsubstrates; filter feeds on plankton andorganic debris by waving cirri (frillyappendages) through an opening on top ofits shell; at low tide, the plates shut tight toprevent its drying out; is a hermaphrodite.


Crustaceans possess an exoskeleton (which theymolt), three body segments, and bilateral sym-metry. These “armored” arthropods are adaptedto a variety of marine habitats.

Homework Assignment

Read pages 240–249 (top). Answer Section Reviewquestions 1–3 on page 243 and 1–3 on page 249,and Chapter Review question 6 on page 255.


Aim: How diverse are the arthropods?



1. Identify the different classes of arthropods.

2. Describe the characteristics of each class.

3. Discuss diversity among the arthropods.


Display specimens or show pictures of differentarthropods. Have students describe the similari-ties among them.


1. All arthropods possess an exoskeleton, jointedappendages, segmented body, and bilateralsymmetry. But there are significant enoughdifferences among them for taxonomists toclassify the arthropods into three main classes.The three different classes are Crustacea,Merostomata, and Insecta.

2. WRITE THE AIM: What do we know about diver-sity among arthropods? Organize the class intofive groups, with each team researching a dif-ferent arthropod. Information on the arthro-pods can be found on the following pages:spider crab (241–242), beach flea (245–246),sea roach (245–246), horseshoe crab (249–251), and sand fly (252). Have students drawtheir arthropod and describe its characteristics.

3. Send a student from each group to the boardto read their findings aloud and to write downsome key facts about their arthropod. All stu-dents should copy the information into theirnotebooks.

4. Some important facts about the arthropodsthat may be overlooked by the students, butthat you may want to mention, are:

■ Spider crab (genus Libinia, class Crustacea):has two body segments (cephalothorax andabdomen); has five pairs of legs (like alltrue crabs); breathes by means of gills; hasopen circulatory system; has antennae, andeyes on stalks; has ventral nerve cord; lackspaddlelike appendages for quick swim-ming, so it crawls slowly along seafloor.

■ Beach flea (genus Talorchestia, class Crus-tacea): type of amphipod; body is com-pressed laterally; lives under moistseaweeds in the strand line on beaches,Canada to Florida; hops and darts about ifdisturbed.

■ Sea roach (genus Ligia, class Crustacea): typeof isopod; body is flattened (top to bottom);swims and crawls among seaweeds androck crevices along shore; is active at night,and hides during the day; some are para-sitic, attaching to the skin and gills of codand halibut.


■ Sand fly (genus Culicoides, class Insecta): likeall insects, has three pairs of legs; has threebody segments; has wings; so tiny, it’s com-monly called “no-see-um”, inhabits inlandbays and marshes where wave impact isslight.

■ Horseshoe crab (genus Limulus, class Meros-tomata): is not a true crab; lacks antennaeand mouthparts; has six pairs of legs; inlate spring, hordes of horseshoe crabsinvade the beaches from Maine to Califor-nia to lay their eggs in the sand. The horse-shoe crab is referred to as a “living fossil”because it has hardly changed at all in itsmore than 400 million years on Earth.


The arthropods are organized into several classes,based on their structural differences. Theseinclude the Crustacea (e.g., lobsters, crabs, barna-cles, and copepods), Merostomata (horseshoecrab, related to scorpions and spiders); and theInsecta (true insects).

Homework Assignment

Read pages 249–252. Answer Section Reviewquestions 1–3 on page 252, and Chapter Reviewquestion 7 on page 255. (See also Chapter Reviewpages 257–258 for additional homework ques-tions.)

Chapter 11/Echinoderms

INTRODUCTION

In Chapter 11, students will learn about the echinoderms, an exclusively marine group of invertebrates. Theechinoderms are characterized by their spiny skin (the spines are more pronounced in some members of thephylum) and their radial symmetry. There are five classes of echinoderms; they exhibit a range of feedinghabits and adaptations. Students will learn about the water vascular system (in the sea star), the role of tubefeet in feeding and locomotion, and about methods of reproduction and regeneration in echinoderms.

■ All echinoderms are marine animals (no freshwater species).

■ Echinoderms have a spiny skin, radial symmetry, and an internal skeleton.

■ Some echinoderms are sessile; others are capable of movement.

■ Tube feet are important in feeding and/or in locomotion. Some echinoderms are filter feeders; others areactive predators.


Aim: How does the sea star carry out its lifefunctions?



1. Explain how the sea star carries out its lifefunctions.

2. Classify the sea star in its correct taxonomicgroup.

3. Describe structures and their functions in thesea star.


Display drawings or specimens of sea stars. Elicitfrom students why the term “starfish” is not anappropriate name for this animal.


Structure Function

Spines Protection

Mouth Ingestion

Water vascular system Locomotion

Stomach Digestion

Digestive gland Digestion

Gonads Reproduction

Skin Breathing

Eyespots Sensitivity


1. The term “starfish” is not appropriate for thesea star because it is an invertebrate, not a fish.The sea star belongs to class Asteroidea, a groupof spiny-skinned animals that is classified inphylum Echinodermata. Point out that echino-derm means “spiny skin.” Most sea stars havefive arms (some have more), which divergefrom a central point, giving the animal radialsymmetry. Sea stars are bottom-dwelling inver-tebrates with an internal skeleton. They arefound from the subtidal zone to the deepestparts of the ocean.

2. WRITE THE AIM: How does the sea star carry outits life functions? Use a wall chart, drawing, orprojection of a sea star’s anatomy for the stu-dents to copy into their notebooks. (You canalso direct students to Figure 11-3 on page262, and Figure 11-4 on page 263.) Draw twocolumns on the board, labeled Structure andFunction. Ask key questions (e.g., How does thesea star move?, How does it ingest food?, andHow does the sea star breathe?) to introduce anddiscuss each life function. Point out eachstructure as you discuss its function, and elicitstudent response as you fill in both columnswith the appropriate information. Have stu-dents copy the completed chart into theirnotebooks.

3. KEY QUESTION: How does the sea star repro-duce? Sea stars have separate sexes. Fertiliza-tion and development occurs externally. Sea

stars can also reproduce asexually by regenera-tion. If an arm is torn off in a fight, a wholenew sea star can grow back from the severedarm provided part of the central disk region ispresent.

4. KEY QUESTION: How does the sea star move? Anetwork of water-filled canals and tubes calledthe water vascular (or hydrovascular) system car-ries out locomotion. Water enters the sea starthrough the sieve plate and passes through thering canal and radial canal to the tube feet. Thetube feet, located in grooves on the ventral sideof each arm, are equipped with a suction disk,which they use to cling to hard surfaces. Theexit of water from the tube feet (back into theampullae) creates the suction that holds thesea star to a substrate. The sea star uses thissuction force to push and pull itself along.


The sea star is a bottom-dwelling invertebratethat is characterized by having a spiny skin andradial symmetry. It has a unique water vascularsystem and tube feet that enable it to carry out avariety of life functions, such as feeding and loco-motion.

Homework Assignment

Read pages 259–265 (top). Answer Section Reviewquestions 1–3 on page 261 and 1–3 on page 265.

LESSON 2 (pages 265–268, 270–271)

Aim: How diverse are the echinoderms?



1. Identify the different echinoderm types.

2. Discuss diversity among the echinoderms.

3. Compare and contrast form and functionamong the echinoderms.



Display specimens or show pictures of differentechinoderms. Describe the similarities amongthem.


1. All echinoderms possess an endoskeleton andhave tube feet for locomotion and/or feeding.But they vary considerably in body form andin their ways of life.

2. WRITE THE AIM: How diverse are the echino-derms? Organize the class into five groups,with each team researching a different echin-oderm. Information on the five types of echin-oderms covered in this lesson can be found onthe following pages: sea urchin (265–267), andsand dollar (265, 267), brittle star (268–270),sea lily (270), and sea cucumber (270–271).

3. Have the students draw their echinoderm anddescribe its characteristics. Send a studentfrom each group to the board to sketch theechinoderm, read their findings aloud, andwrite down some key facts about their echino-derm. All students should copy the informa-tion into their notebooks.

4. Some important facts about the echinodermsthat you may want to see mentioned are:

■ Sea Urchin (Class Echinoidea): inhabitsintertidal and subtidal zones along rockycoasts, grazing on algae on the rock sur-faces; spines are attached to its endoskele-ton, or test, which is left behind after itdies; its spines protect against most preda-tors.

■ Sand Dollar (Class Echinoidea): looks like alarge coin covered by a thin, spiny skin;oval disk is left behind after it dies; feeds bycatching plankton and organic debris insticky strings beneath its spines.

■ Brittle Star (Class Ophiuroidea): is a solitaryanimal that lives under rocks in the inter-tidal zone (from arctic to tropics); alsoinhabits deep seafloor to depths of 800meters; has muscles in its long, flexiblearms, which are used for quick movementalong the seafloor and to help catch bits offood; has a flattened central disk; like thesea star, can regenerate missing arms.

■ Sea Lily (Class Crinoidea): its body is com-posed of feathery arms perched atop astalk, which is attached to a substrate; filterfeed by waving its arms and catchingplankton in the tube feet (which then passit to the mouth).

■ Sea Cucumber (Class Holothuroidea): lacksendoskeleton and spines, but has smallbony pieces in its skin; has tube feetarranged in five rows, which it uses formovement and to catch food; lives onsandy and rocky seafloors in intertidal andsubtidal zones and at great depths; usessticky, branching tentacles around itsmouth (which retract when disturbed) totrap bits of food; has one-way digestivetract.


The echinoderms are a diverse group of spiny-skinned marine invertebrates. All are bottom-dwelling animals; most are capable of movement;and they feed on organisms found in the sedi-ment or in the currents of water.

Homework Assignment

Read pages 265–268, 270–271. Answer SectionReview questions 1–3 on page 267 and 1–3 onpage 271. (See also Chapter Review pages 276–277for additional homework questions.)

43

UNIT 4 MARINE VERTEBRATES

Chapter 12/Marine Fishes

INTRODUCTION

Chapter 12 covers the three classes of fishes—the topic that may be of most interest to students of marine sci-ence. There are thousands of species of fishes; they are the most numerous vertebrates in the ocean. Studentswill learn about the distinguishing features of protochordates, jawless fishes, cartilaginous fishes, and bonyfishes. Basic anatomy, life functions, and life cycles are covered, in addition to unusual adaptations in bonyfishes.

■ There are three classes of fishes: jawless, cartilaginous, and bony. Fish are aquatic; have scales, fins, and gills;and are (mostly) cold-blooded.

■ Jawless fishes lack jaws and a backbone; the lamprey also lacks scales.

■ Cartilaginous fishes have a skeleton of cartilage, visible gill slits, spiracles, placoid scales, a lateral line organ,and no swim bladder.

■ Bony fishes have a skeleton of bone, mucus-covered scales over their skin, a swim bladder, and gills coveredby an operculum.

■ Some fishes bear live young; others lay eggs (or egg cases).

■ Bony fishes are found in every type of aquatic environment.


Aim: What do we know about the proto-chordates?



1. Identify the protochordates.

2. Classify the protochordates.

3. Describe structure and function in the proto-chordates.


Display or draw a picture on the board of alancelet. Ask the students: How would you classifythis organism?


1. Animals that possess a dorsal nerve cord, a rod-like notochord, and gill slits at some point intheir development are called chordates andbelong to the phylum Chordata. The lancelet,tunicate, and acorn worm have these struc-tures during development (only the lanceletretains all three in its adult form), but lack cer-tain advanced traits; so they are classified inthe subphylum Protochordates. The vertebrate(i.e., having a backbone) chordates include allfish, amphibians, reptiles, birds, and mam-mals. The protochordates represent an evolu-tionary link between vertebrates andinvertebrates.

2. WRITE THE AIM: What do we know about theprotochordates? Organize the class into three


groups, with each team researching a differentprotochordate. Information on the lancelet,tunicate (sea squirt), and acorn worm can befound on pages 281–283.

3. Send a student from each group to the boardto sketch their protochordate, write downsome key facts about it, and describe its char-acteristics to the class. All students shouldcopy the information into their notebooks.

■ Lancelet (genus Amphioxus): tiny and trans-parent; fishlike in appearance; adult formretains dorsal nerve cord, notochord, andgill slits; lives half-buried in the sand, withhead sticking out to filter plankton; hassexual reproduction (via separate sexes).

■ Sea Squirt (genus Molgula): found world-wide; encrusts substrates such as the under-sides of floating docks; squirts water whendisturbed (hence its name); also called tuni-cate because of its clear, tough, outer mem-brane, or tunic; larval form has dorsalnerve cord, notochord, and gill slits, whichdisappear in the adult form; has sexualreproduction (hermaphrodite).

■ Acorn Worm (genus Saccoglossus): adultform retains dorsal nerve cord and gill slits;burrows in the sand in intertidal and subti-dal zones, where it feeds on organic debris;expels the indigestible sand in small lumps(or casts) on the seafloor.


Have students read aloud the information aboutprotochordates that they have written on theboard and in their notebooks.

Homework Assignment


LESSON 2 (pages 280, 283–285, 290–292)

Aim: How are the marine fishes classified?



1. Classify the marine fishes.

2. Compare and contrast the different types offish.

3. Identify the fishes’ distinguishing characteris-tics.


Display models or pictures of a jawless fish, ashark, and a typical bony fish. Have studentsobserve and describe these different fishes.


1. All fish possess gills for breathing, fins forswimming, and a scaly skin for protection. Tellstudents that the animals on display representthe three different classes of fish.

2. WRITE THE AIM: How are the marine fishes clas-sified? The fishes are placed in three differentclasses based on differences in structure (andevolutionary history). These groups are thejawless fishes, the cartilaginous fishes, and thebony fishes.

3. Organize the class into three groups, with eachteam researching a different class of fish. Infor-mation about these fish (and labeled diagramsof each type) can be found on the followingpages: jawless fish (283–284), cartilaginous fish(284–286, 289), and bony fish (290–292).

4. Send a student from each group to the boardto sketch their fish and to write down key factsabout it. All students should copy the infor-mation into their notebooks.

5. Some important facts about these fish that youmay want to see mentioned are:

■ Jawless Fishes (Class Agnatha): first jawlessfish evolved from invertebrates; lack a truebackbone; possess a notocord for support;live as parasites by attaching to, and feed-ing on the blood and tissues of, a host fish;includes sea lamprey and hagfish.

UNIT 4 / MARINE VERTEBRATES 45

■ Cartilaginous Fishes (Class Chondrichthyes):approximately 600 species; skeletons com-posed of cartilage; have placoid (teethlike)scales; lack gill covers (operculum); lackswim (gas) bladder; have spiracles (breath-ing holes) behind the eyes; have a ventralmouth; pores in shark’s snout containnerve receptors that pick up electrical cur-rents; lateral line organ detects vibrationsin water; have internal fertilization.

■ Bony Fishes (Class Osteichthyes): more than15,000 species of bony fishes (marine andfreshwater); skeletons composed of bone;backbone made up of individual bonescalled vertebrae, which surround and pro-tect the spinal cord; possess mucus-coveredscales, which have growth lines that formbands (circuli), are used to determine theage of the fish; have gill covering called theoperculum; have swim (gas) bladder.


Have a student leader from each group read aloudthe information that has been written on theboard.

Homework Assignment

Read pages 280, 284–286, 290–292. Answer Sec-tion Review questions 1–3 on page 290, andChapter Review question 6 on page 304.


Aim: How does a bony fish carry out its lifefunctions (re: external anatomy)?



1. Identify a fish’s external structures that carryout life functions.

2. Explain how these life functions of the fish arecarried out.


Show a live bony fish (in classroom aquariumtank) or display a model of a typical bony fish.Elicit from students a list of the basic (external)life functions carried out by the fish.


1. A fish exhibits observable life functions suchas locomotion (swimming), nutrition (feed-ing), breathing (movement of gills), andresponse to stimuli in environment.

2. WRITE THE AIM: How does a bony fish carry outits life functions? In this lesson, you will focuson an understanding of the external anatomyof a bony fish. Display a wall chart, diagram(see Figure 12-12, on page 292 in the text), orprojection of a bony fish for the students tocopy into their notebooks.

3. Draw two columns on the board, labeled Struc-ture and Function. Ask key questions (e.g.,How does the fish sense its environment?, Howdoes a fish swim?, and How does a fish breathe?)to introduce and discuss each life function.Point out each structure as you discuss itsfunction, and elicit student response as you fillin both columns with the appropriate infor-mation. Define each function on the board.Have students copy the completed chart intotheir notebooks.


Have a student go to the board and draw a bonyfish. Call on students to name the different partsof the fish. Have other students define each struc-ture and its function.

Homework Assignment




Aim: How does a bony fish carry out its lifefunctions (re: internal anatomy)?



1. Identify a fish’s internal structures that carryout life functions.

2. Explain how these life functions of the fish arecarried out.


Display a model or chart that shows the internalanatomy of a typical bony fish. Elicit from stu-dents a list of the basic (internal) life functionscarried out by the fish.


1. Fishes, like all other vertebrates, have internalstructures and systems that are needed to carryout their life functions (such as circulation,digestion, and reproduction).

2. WRITE THE AIM: How does a bony fish carry outits life functions? In this lesson, you will focuson an understanding of the internal anatomyof a bony fish. Display a wall chart, diagram(see Figure 12-12 on page 292), or projectionof a bony fish for the students to copy intotheir notebooks.

3. Draw two columns on the board, labeled Struc-ture and Function. Ask key questions (e.g.,How does a fish digest food?, How are its nutri-ents transported?, and How does a bony fishreproduce?) to introduce and discuss each lifefunction. Point out each structure as you dis-cuss its function, and elicit student responseas you fill in both columns. Define each func-tion on the board. Have students copy thecompleted chart into their notebooks.


Call on students to go to the board to point outand name important internal structures of a bonyfish. Have other students define each structureand its function.

Homework Assignment

Read pages 294–298 (top). Answer ChapterReview questions 7 on page 304 and 12–20 onpage 306.


Aim: What are some special adaptations ofmarine fishes?



1. Identify adaptations in different types ofmarine fish.

2. Explain how the fishes’ adaptations aid theirsurvival.


Show the class a picture or projection of the por-cupine fish (genus Diodon). Describe how this ani-mal is adapted to survive in its environment.


1. The porcupine fish is one of many fish that isequipped with unique structures that enable itto survive in its environment. Specifically, theporcupine fish can inflate its spine-coveredbody with water so that it becomes a spiky ballthat deters predators.

2. WRITE THE AIM: What are some special adap-tations of marine fishes? There are many uniqueand surprising adaptations among the fishes,which aid survival in a variety of marine habi-tats. Organize the class into six groups, with


each team researching a different fish. Infor-mation on, and illustrations of, these unusualfish can be found on the following pages:flounder (298), sea horse (299), flying fish(299), anglerfish (299–300), mola (300–301),and coelacanth (300–301).

3. Send a student from each group to the boardto sketch their fish and to write down key factsabout it. All students should copy the infor-mation into their notebooks.

4. Some important facts about these fish that youmay want to see mentioned are:

■ Flounder (genus Platichthys): flattened bodyshape; uses camouflage to match its ben-thic surroundings; pigments in its skin cellsexpand and contract to match the environ-ment; adult has both eyes on the same(dorsal) side of its head.

■ Sea Horse (genus Hippocampus): uses itslong tail to wrap around a piece of seaweedor marsh grass; uses its snout like a straw tosuck up plankton and food particles; thefemale releases eggs into the male’s broodpouch; after two weeks of incubation, the“pregnant” father expels baby sea horsesinto the water.

■ Coelacanth (genus Latimeria): up to twometers in length; once thought to beextinct, it was rediscovered in the deepwaters of the Indian Ocean; has paddlelikefins similar to those of the ancestral lobefinfishes; considered rare, it is protected bylaw.

■ Flying Fish (genus Cypselurus): relativelysmall fish; can jump out of the water ashigh as 12 meters and “fly” for 30 meters,propelled by the action of its pectoral fins.which beat like wings.

■ Deep-sea Anglerfish (genus Melanocetus):lives at depths of 500 to 2000 meters; hashuge mouth with spiky teeth to catch prey;has a dangling bioluminescent lure toattract prey and/or potential mates.

■ Mola (genus Mola): up to three meters inlength; also called ocean sunfish; usuallylies on its side near the ocean surface, feed-ing on jellyfish, small fish, and plankton;caudal fin and posterior region of the bodyare much reduced in size; slow-moving andvulnerable to predation by humans andkiller whales; the female produces millionsof eggs, thereby ensuring the species’ sur-vival.


Have a team leader from each group read aloudthe description of their fish. Be sure to emphasizeeach fish’s unique adaptations.

Homework Assignment

Read pages 298–301. Answer Section Reviewquestions 1–3 on page 301, and Chapter Reviewquestions 8 on page 304 and 22–24 on pages306–307.

Chapter 13/Marine Reptiles and Birds

INTRODUCTION

While reading Chapter 13, students may be surprised to learn the extent of marine adaptations that are seenamong some birds and reptiles. Descended from land-adapted animals, the marine birds and reptiles exhibita fascinating array of adaptations that reflect their adjustment to life in and around the sea. Marine reptiles,being cold-blooded, are found mainly in tropical regions; marine birds, being warm-blooded, are foundthroughout the world. Students will learn about adaptations of reptiles and birds to a range of marine habitats.


■ Reptiles are ectothermic; birds are endothermic. Both exhibit specific adaptations to ocean environments,such as having salt glands.

■ Marine reptiles live mainly in tropical and subtropical oceans.

■ Reptiles have a dry, scaly skin that protects against water loss.

■ Like birds, most reptiles lay eggs (some reptiles live-bear young).

■ Aquatic birds have waterproof feathers that help insulate their bodies.

■ Birds show a variety of adaptations in the structure and function of their beaks, wings, and feet, for feedingin and around the sea.


Aim: How are marine reptiles adapted totheir environment?



1. Identify the different marine reptiles.

2. Describe adaptations in marine reptiles.

3. Explain how these adaptations aid the reptiles’survival.


Show the class a picture or model of a marine rep-tile (e.g., a crocodile or sea turtle). Ask students todescribe its (external) characteristics.


1. All reptiles have a thick, dry scaly skin andbelong to class Reptilia. Some reptiles, such asthe specimen shown, live in saltwater habitats;so they are called marine reptiles. These includethe crocodile, sea turtle, sea snake, and marinelizard.

2. WRITE THE AIM: How are marine reptiles adaptedto their environment? Most reptiles have to livein warm climates because they are ectothermic,and they cannot tolerate wide temperatureranges. Reptiles depend on the external tem-perature (of the air and water) to regulate thetemperature of their “cold-blooded” bodies.

3. Organize the class into four groups, each teamresearching a different marine reptile. Infor-mation on the reptiles can be found on thefollowing pages: saltwater crocodile (310–311),sea snake (310–311), marine lizard (311–312),and sea turtles (313–317). Have students drawtheir reptile and describe its adaptations intheir notebooks.

4. Some important facts about marine reptilesthat you may want to see mentioned are:

■ Crocodile (order Crocodilia): American salt-water crocodile (genus Crocodylus) lives inthe Florida Keys; up to five meters inlength; has a four-chambered heart (likebirds); the female guards her eggs in nestuntil they hatch; is an endangered species,only about 1000 remain; hunts by remain-ing just below the water’s surface (withonly its eyes and nostrils protruding) toambush prey; resembles alligators, exceptthe crocodile’s snout is longer and nar-rower.

■ Sea Snakes (order Squamata): about 50 dif-ferent species; from one to two meters inlength; all inhabit tropical oceans; somehunt fish, others eat fish eggs; are ven-omous, but not very aggressive; have a pad-dlelike tail to aid in swimming; salt glandsin the mouth enable snake to excreteexcess salts and maintain water balance;have a special flap of tissue to cover thenostrils during dives; the lungs can inflateto 3⁄4 body length, to enhance capacity tohold air underwater; some live-bear youngin the sea, others lay their eggs on land.


■ Marine Lizard (order Squamata, genusAmblyrhynchus): only marine lizard is themarine iguana; inhabits the GalàpagosIslands; swims and feeds on marine algaethat grow on rocks in the subtidal zone;movements underwater are very graceful;has a flattened tail to aid in swimming;when cold, warms up by basking on rockson land.

■ Sea Turtles (order Chelonia): six species, allare endangered; most widely distributedmarine reptile; inhabit tropical and warmtemperate oceans worldwide; species can bedistinguished by the pattern of scales ontheir shell; have no teeth, but do havepowerful jaws; feed on jellyfish, algae, crus-taceans, and turtle grass; born on land, butspend their lives at sea; fertilization is inter-nal and development is external.


Near the end of the period have a student fromeach group draw their marine reptile on theboard and have another student describe its spe-cial adaptations. All students should copy theinformation into their notebooks.

Homework Assignment

Read pages 308–317. Answer Section Reviewquestions 1–3 on page 317, and Chapter Reviewquestions 6–7 on page 326 and 12–17 on page328.


Aim: How are marine birds adapted to theirenvironment?



1. Identify the different marine birds.

2. Describe adaptations in marine birds.

3. Explain how these adaptations aid the birds’survival.


Show students a picture or model of a marine bird(e.g., a sea gull or cormorant). Ask students todescribe its (external) characteristics.


1. All birds have feathers and belong to classAves. The feathers and hollow bones (found innearly all species) are adaptations for flight.Marine birds have special adaptations for liv-ing in and near the sea, and for feeding in thesea or on shore. All birds reproduce on land(internal fertilization) and lay eggs (externaldevelopment).

2. WRITE THE AIM: How are marine birds adaptedto their environment? All birds have down feath-ers (for insulation) and contour feathers (forflight). Some aquatic birds also have powderfeathers, which help repel water and protectthe underlying down feathers. Some birds alsohave a gland near the tail that produces awaterproof oil, which is used to conditiontheir feathers. Birds are endothermic, so theycan maintain a stable internal temperatureeven when the air or water temperature varieswidely. Many aquatic and marine birds havewebbed feet to aid movement in the water.

3. Organize the class into six groups, each teamresearching a different marine bird. Informa-tion on these birds can be found on the fol-lowing pages: snowy egret (319), sea gull (320),brown pelican (320–321), black skimmer(321), osprey (321), and penguin (322–323).Have students draw their marine bird anddescribe its adaptations in their notebooks.

4. Some important facts about the marine birdsthat you may want to see mentioned are:

■ Snowy Egret (genus Egretta): inhabits saltmarshes from Maine to California; has along flexible neck and pointed bill, used tospear small fish; the long stiltlike legs for


wading give it the advantage of spottingfish from above.

■ Sea gulls (genus Larus): several differentspecies; prefer isolated nesting places onoffshore islands; scavenge along the shoreof mainland beaches for dead marine ani-mals carried in by the tides; also eat crabson the beach and garbage at landfills.

■ Brown Pelican (genus Pelecanus): large,once-endangered bird; dives into the oceanto scoop up fish in its large throat pouch;water is squeezed out of the pouch and thefish is swallowed headfirst (so its dorsalspines don’t get stuck in the bird’s throat);found in tropical regions, e.g., Florida Keys.

■ Black Skimmer (genus Rynchops): fishes “onthe wing” by flying low over the water; thetip of its lower jaw, which juts out, skimsthe surface for fish; it swallows the fishwhole, while still in flight.

■ Osprey (genus Pandion): also called fishhawk (feeds only on fish), lives along U.S.coastlines; has keen vision to spot fish fromhigh up; has strong curved claws (talons)for grasping fish; has long, powerful wingsthat enable it to swoop down from its nest

and grab fish from the water, while it is stillin flight.

■ Penguins (several genera): several species;the most aquatic of all seabirds; native onlyto the southern hemisphere; have lost theability to fly; their wings have evolved intoflippers that let them “fly” through thewater; bones are dense (not hollow), whichgives them the weight necessary for deepdives; have several layers of down feathersand a thick layer of fat to trap body heat,which helps them survive in the Antarctic.


Near the end of the period have a student fromeach group draw their marine bird on the boardand have another student describe its specialadaptations. All students should copy the infor-mation into their notebooks.

Homework Assignment


Chapter 14/Marine Mammals

INTRODUCTION

Chapter 14 covers the group of animals probably most beloved by students of marine science: cetaceans,pinnipeds, and other marine mammals. Like ourselves, the marine mammals are warm-blooded, air-breathing,nurse their young, and, in general, are intelligent. However, unlike humans, they spend their whole lives in, orvery closely tied to, the sea. Thus, they have special adaptations for swimming, feeding, diving, and commu-nicating in the ocean.

■ Marine mammals are warm-blooded, air-breathing vertebrates.

■ Whales and dolphins are fully aquatic, feeding and breeding in the water. They have blubber to keep themwarm, and special adaptations for communicating underwater and for deep diving.

■ Seals and sea lions, which are carnivores, swim and feed in the ocean, but come ashore each year to mateand rear their young.


■ Other marine mammals, such as sea otters and manatees, breed in the water. They show other adaptationsto marine habitats.

■ Many species of marine mammals have become endangered or threatened due to human activities. Lawsnow protect them.

■ The diving response is a special adaptation of marine mammals.

LESSON 1 (pages 331–333, 341–346, 348–349)

Aim: How are the marine mammals classi-fied?



1. Identify the marine mammals.

2. Classify the marine mammals.

3. Compare and contrast marine mammals.


Display several models or photographs of marinemammals, such as a whale, seal, otter, dolphin,walrus, and so on. Have the students compareand contrast their features.


1. All mammals have mammary glands to feedtheir newborns, a four-chambered heart, and(usually) a fur or hair covering. Mammals areendothermic (warm-blooded); they have a sta-ble internal body temperature. Mammals areall placed in class Mammalia.

2. WRITE THE AIM: How are the marine mammalsclassified? The marine mammals are classifiedwithin several taxonomic categories calledorders (and suborders). These include: orderCetacea (whales, dolphins, porpoises); orderCarnivora, suborder Pinnipedia (seals, sea lions,walrus); order Carnivora (sea otter, polar bear,and many land carnivores); and Sirenia (man-atees, dugongs).

3. Organize the class into four groups, with eachteam researching a different group of marine

mammals. Basic information about eachgroup can be found on the following pages:cetaceans (331–333), pinnipeds (341–344),marine carnivores (344–345, 349), and sireni-ans (346, 348–349). Have students draw theirmarine mammal and describe its adaptationsin their notebooks.

■ Cetaceans: about 80 different species; allhave a completely aquatic way of life; thebiggest is the blue whale; the smallest aredolphins and porpoises (See Figure 14-1);comprised of two main groups—baleen(suborder Mysticeti) and toothed (suborderOdontoceti). Baleen whales feed on plank-ton and small animals (see Figures 14-2 and14-3); toothed whales (including dolphins& porpoises) have peglike teeth for catch-ing larger animals such as fish, squid, andseals. The sperm whale is the largesttoothed whale; the narwhal is the smallesttoothed whale (see Figure 14-4).

■ Pinnipeds: “feather-footed” marine carni-vores include seals, sea lions, and walruses;come ashore each year to mate and bearyoung; sea lions have external ear flapsand seals do not; seals and sea lions eat fishand other marine life; the walrus (genusOdobenus) inhabits the Arctic and sub-Arctic; walrus has tusks, used to dig up mol-lusks, haul-out on ice, and for dominance(among males); feeds mostly on benthicmollusks and other invertebrates, whichthey locate with their sensitive whiskers.

■ Marine Carnivores: all carnivores havesharp teeth for seizing and tearing flesh.The polar bear (genus Ursus): mainly terres-trial, but is most aquatic of all bears; excel-lent swimmer (has streamlined head); lives


on ice floes and along the coast in the Arc-tic; has dense fur and a thick layer of blub-ber for insulation; hunts seals and fish. Thesea otter (genus Enhydra): smallest of allmarine mammals; most aquatic member ofthe weasel family; lives in kelp beds alongthe coast from Alaska to California; feedson shellfish (e.g., sea urchins, abalone),which it opens by smashing against a rock(held against stomach while floating on itsback); has no blubber, but has very thickfur.

■ Sirenians: inhabit warm coastal waters;manatee, or sea cow, (genus Trichechus)feeds on vegetation in shallow rivers andcoastal waters of Florida, Caribbean, andthe Amazon River; uses its upper prehensilelip to grasp vegetation; moves slowlythrough the water, using up-and-downmovement of its flat tail; endangered, fewerthan 1000 manatees left in Florida waters;many are injured and/or killed by speedingboats; dugongs (related marine herbivores)live off the coast of West Africa.


Have a student from each team go to the boardand sketch a representative animal or two fromtheir marine mammal group. Have another stu-dent describe its special adaptations. All studentsshould copy the information into their note-books.

Homework Assignment

Read pages 330–333, 341–346, 348–349. AnswerSection Review questions 1–3 on page 350, andChapter Review questions 6–8 on page 355.

LESSON 2 (pages 331–336, 339–342)

Aim: How are whales adapted to their envi-ronment?


1. Identify adaptations in whales to the marineenvironment.

2. Explain how the adaptations enhance thewhale’s survival.

3. Describe how whale structures are related totheir functions.


Display a photo or drawing of a baleen whale andof a toothed whale, or refer students to Figure14-3 (on page 332) and Figure 14-5 (on page 335)in their textbooks. Have them copy and labeldrawings of these whales in their notebooks.


1. Whales (whose ancestors lived on land 50 mil-lion years ago) have a variety of structures, oradaptations, that aid their survival in themarine environment. For example, whaleshave a blowhole for breathing, and flippers forswimming.

2. WRITE THE AIM: How are whales adapted totheir environment? Focus on the two types ofwhales shown in Figures 14-3 and 14-5.

KEY QUESTIONS: What do whales eat? Discussthe two main types of whales: baleen andtoothed. Baleen whales use plates of baleen,which hang from the roof of their mouth, tofilter plankton and small fish from the water.The throats of some baleen whales are pleatedto expand while they are feeding. Toothedwhales have peglike teeth (on either one orboth of their jaws), which are used to catchprey such as fish, seals, penguins, and squid.

3. KEY QUESTION: How does a whale breathe? Allcetaceans have a blowhole on the top of theirhead. The blowhole is the whale’s nose; itsdorsal location enables the whale to breathewhile it remains submerged (and still able tosee things underwater).

4. KEY QUESTION: How does a whale swim? Vig-orous contractions of the body’s muscles cause


up-and-down movements of the tail fluke,which propel the whale through the water.The pectoral fins (flippers) are used for steer-ing and balance. The fastest of all marinemammals, the killer whale (Orcinus) has beenclocked at 55 kph.

5. KEY QUESTIONS: How does a whale keep warm?Besides being endothermic (like all othermammals), whales have a thick layer of fat,called blubber, under the skin, which trapsbody heat.

6. KEY QUESTIONS: How do whales communicate?Whales use sound to communicate; smallerwhales (e.g., narwhals and dolphins) producehigher-frequency sounds (like whistles). Largerwhales produce lower-frequency sounds,which travel farther. Sounds are produced inthe whale’s airway and are emitted through aspongy mass of tissue in the forehead, calledthe melon. (Sound is also used in feedingbehavior.)

7. KEY QUESTIONS: How do whales reproduce?Whales reproduce in the water. Whales havespecial breeding grounds where they congre-gate to calve and mate. Fertilization and devel-opment are internal. The period of embryonicdevelopment may last from 11 to 18 months.There is a close bond between the mother andoffspring; the calf nurses for six to ten monthson a very high-fat, high-protein milk.


Organize the class into six groups; with each teamassigned a different adaptation to summarize.Have a student from each group read theirdescription to the class. All students should copythe information into their notebooks.

Homework Assignment

Read pages 331–336 (top) and 339–342 (top).Answer Section Review questions 1–3 on page334 and question 3 on page 341.


Aim: How do whales behave?



1. Describe behaviors in the whale.

2. Explain why whales migrate.

3. Compare migration in gray whales and hump-back whales.


Project on an overhead the migratory routes ofgray whales and humpback whales, as shown inFigure 14-8 on page 338. Have students copy thisinfo into their notebooks.


1. The kinds of responses that an organismmakes to its environment are called behavior.Animals respond to their environment bybehaving in a variety of adaptive ways.

2. WRITE THE AIM: How do whales behave? Pro-ject or display to the class the following exam-ples of whale behavior (as shown in Figure14-7 on page 337).

■ Diving: Whales dive beneath the surface ofthe ocean largely in pursuit of food. Thepectoral fins (flippers) are used to changefrom a horizontal to a vertical position. Thehead submerges first and then the body,propelled downward by the action of thetail fluke, which is the last part of the bodyto submerge.

■ Lobtailing: When lobtailing, a whale wavesits tail in the air and then smashes itagainst the surface of the ocean, producinga sound that can be heard several kilome-ters away. Some marine scientists believethat lobtailing is a sign of aggression. Oth-ers think that it is the whale’s way ofannouncing its presence.


■ Spyhopping: When spyhopping, a whaleraises its head above the water surface tolook around for a few seconds. It appearsthat whales are curious about the worldabove the ocean. Scientists do not fullyunderstand the purpose of this behavior.

■ Breaching: This most spectacular kind ofbehavior occurs when a whale leaps almostcompletely out of the water and thencrashes down, creating a huge, loud splash.Scientists are not sure why whales breach.There are several possible reasons forbreaching, such as: to dislodge parasitesfrom the skin, as a form of communica-tion, or just a playful type of behavior.

■ Migrating: Whales, like the humpbackwhale and gray whale, shown in Figure14-2 on page 332, travel, or migrate, yearlyover long distances in a group (the pod) toreach either their feeding or breedinggrounds.

3. KEY QUESTION: Why do whales migrate? TheCalifornia gray whale (genus Eschrichtius)migrates yearly from its from feeding groundsoff Alaska to its breeding grounds off Baja Cal-ifornia, and back again—a round-trip distanceof more than 12,000 km. Gray whales spendthe summer months feeding in the cold Arc-tic Ocean, where the nutrient-rich waters pro-duce an abundance of plankton. During thewinter, they migrate to the warm, shallowwaters around Baja California, where theybreed and bear their young. The Atlantic pop-ulation of the humpback whale (genusMegaptera) migrates yearly from its feedinggrounds off Iceland to its breeding grounds inthe Caribbean Sea. The Pacific populations ofhumpbacks migrate from the Bering Sea tosouthern Mexico; others breed in the pro-tected waters of Hawaii.


Divide the class into five groups, with each teampreparing a summary of one of the followingbehaviors: diving, spyhopping, breaching, lob-

tailing, and migration. Have the team leadersfrom each group read their summaries aloud tothe class. Encourage class discussion and have thestudents take notes.

Homework Assignment

Read pages 336–340 (top). Answer Section Reviewquestions 1–2 on page 341, and Chapter Reviewquestions 13–17 and 23–24 on pages 356–357.


Aim: How are marine mammals adapted fordeep and prolonged dives?



1. Define the diving response (diving reflex).

2. Describe how the diving response works.

3. Explain how marine mammals can make deepdives.


Project on an overhead or write on the board acopy of Table 14-1, “Depth and Time of Breath-Hold in Diving Marine Mammals,” on page 350,for students to copy into their notebooks.


1. Ask students how long they think humans canstay underwater on a single breath-hold. Themaximum breath-hold for humans is approxi-mately three minutes. Point out the maximumbreath-holds of the five marine mammalslisted in the table. Have students hold theirbreath for 15 seconds as a means of compari-son.

2. WRITE THE AIM: How are marine mammalsadapted for deep and prolonged dives? The spermwhale can dive more than 2000 meters in


depth on a single breath, and stay underwaterfor more than one hour, to pursue prey suchas the giant squid. The physiological changesthat take place in the whale, which enable itto make such deep and prolonged dives, makeup what is called the diving response (or divingreflex).

3. KEY QUESTION: What are the parts of the divingresponse? Part of the diving response is thedetouring, or shunting, of blood that containsfood and oxygen from the rest of the body tothe vital organs. The heart rate also slowsdown as blood is shunted because there is lessblood circulating around the body. The slow-ing of the heart rate, called bradycardia, duringdives in marine mammals, is another part ofthe diving reflex. This slowing helps to con-serve the animal’s energy and oxygen.

4. Have students examine the data table. Askwhy some marine mammals, such as the sealand the sperm whale, have a longer breath-hold than others. The duration of a breath-hold is related to the oxygen-carrying capacityof an animal’s body.

5. KEY QUESTION: Why do marine mammals havea higher oxygen-carrying capacity? Diving mam-mals have a higher blood volume and greaterconcentration of oxygen-binding red bloodcells than do non-diving mammals. The pro-

tein hemoglobin, in red blood cells, holds and transports oxygen. Diving mammals alsohave another oxygen-binding protein, calledmyoglobin, located in the muscles. Together,the hemoglobin and myoglobin increase theoxygen-carrying capacity of the body. In addi-tion, elastic tissue in the lungs and chest per-mits greater lung expansion during inhalation,and enables more complete and rapid inhala-tions and exhalations between dives.


Divide the class into five groups, with each teamrecording a description of one marine mammaladaptation for deep and prolonged dives (brady-cardia, shunting of blood, higher blood volume,myoglobin, elastic tissue in lungs). Have a leaderfrom each group read aloud their description. Allstudents should copy the information into theirnotebooks.

Homework Assignment

Read pages 350–352. Answer Section Reviewquestions 1–3 on page 352, and Chapter Reviewquestions 9–12 on pages 355–356 and 18–22 onpage 357.

56

UNIT 5 THE WATER PLANET

Chapter 15/World of Water

INTRODUCTION

Chapter 15 introduces students to the world of ocean water—its volume, properties as a solvent, variations indissolved oxygen levels, pH levels, salinity, and the importance of such chemical characteristics to the survivalof life in the sea.

■ About 97 percent of Earth’s total water budget is salt water.

■ The special chemical properties of water enabled the evolution and survival of life in the ocean and, ulti-mately, on the land, too.


Aim: What do we know about the geographyof the ocean?



1. Define latitude and longitude.

2. Locate geographical regions using latitude andlongitude.

3. Compare and contrast the sizes of oceans andlandmasses.


Have students draw a pie graph showing themajor oceans: Pacific, Atlantic, Indian, and Arctic.


1. The body of water known collectively as theocean covers about 71 percent of Earth’s sur-face.

WRITE THE AIM: What do we know about thegeography of the ocean? The oceans surround

landmasses called continents. When two conti-nents enclose a part of the ocean, a smallerbody of water called a sea is formed. (Refer toFigure 15-1 on page 361.)

2. The continents divide the ocean into fourmain parts. Draw on the board a pie graphthat shows the relative sizes of the world’s fourmajor oceans: Pacific (the largest ocean),Atlantic, Indian, and Arctic oceans. (Refer toFigure 15-2 on page 364.)

3. KEY QUESTION: What is Earth’s water budget?The total amount of water contained in andon Earth is called the water budget. The oceanscontain about 97 percent of all the water onEarth. The remaining 3 percent is freshwater(i.e., rivers, lakes, and groundwater). The sealevel is the point at which the surface of theocean touches the land. About 12,000 yearsago, during the last ice age, the sea level wasmuch lower because so much water was inglaciers.

4. KEY QUESTION: How is Earth’s surface mapped?Display a wall map and globe of Earth. Thepart of the earth above the equator is thenorthern hemisphere. The part below the equa-tor is the southern hemisphere. The lines that

UNIT 5 / THE WATER PLANET 57

Location Latitude Longitude

Gulf of Mexico 20 degrees N 80 degrees W

Mediterranean Sea 30–35 degrees N 5 degrees W

Iceland 60 degrees N 20 degrees W

Madagascar 20 degrees S 40 degrees E

Japan 30 degrees N 130 degrees E

Alaska 60 degrees N 160 degrees W

Florida 25 degrees N 75 degrees W

Baja California 25 degrees N 105 degrees W

New Zealand 40 degrees S 170 degrees E

Galápagos Islands 0 degrees (equator) 90 degrees W

run parallel are called the lines of latitude. Lat-itude is the distance north and south of theequator, as measured in degrees. The measure,in degrees, of the distance east and west of theprime meridian is the called the longitude.

5. KEY QUESTIONS: How can we locate areas onEarth’s surface? Distribute handouts of maps,showing Earth’s lines of latitude and longi-tude, or refer students to Figure 15-1 (page361).

6. Write the following table on the board foryour students to copy into their notebooks;give only the names of the locations. Organizethe class into five groups, with each team find-ing the approximate latitude and longitude ofthe locations listed in the table.


Have a team leader from each group go to theboard to write in the approximate latitude andlongitude of two geographical regions. Based on the data in table, have students discuss thedistribution of landmasses above and below theequator.

Homework Assignment

Read pages 359–362 and 364–365 (top). AnswerSection Review questions 1–3 on page 362 and 1–2 on page 366.


Aim: What is known about the ocean’swater?



1. Draw and label the water cycle.

2. Explain how a constant sea level is main-tained.

3. Define solute, solvent, and solution.


Draw the water cycle on the board (as shown inFigure 15-3 on page 365), but omit the labels andarrows for evaporation, condensation, and pre-cipitation. Have the students copy the diagraminto their notebooks, and then connect and labelthe parts as the lesson proceeds.


1. WRITE THE AIM: What is known about theocean’s water? The circulation of water—fromthe ocean, into the atmosphere, and backdown again—is called the water cycle. Thethree stages of the water cycle are evaporation,condensation and precipitation. The process


by which liquid water changes to gas (watervapor) is called evaporation. The process ofcloud formation is called condensation. Whenthat water changes to rain, snow, sleet, or hail,it is called precipitation. As a result of the watercycle, a constant sea level is maintained.

2. KEY QUESTION: What is the composition ofocean water? Before class begins, evaporatesome ocean water (or salt water) from an evap-oration dish or glass plate. Show the residue tothe class. The residue is salt.

3. Salt, or any other substance that mixes withwater, is called a dissolved substance. A dis-solved substance is also called a solute. The liq-uid (such as water) that holds dissolvedsubstances is called a solvent. The combinationof water and its dissolved substances is called a solution. The relationship between solute,solvent, and solution can be seen in the fol-lowing word equation: salt (solute) + water(solvent) → salt water (solution).

4. Many solutions like seawater are also calledmixtures. A mixture contains two or more sub-stances that can be separated by ordinaryphysical means. In other words, water (the sol-vent) can be evaporated off from the salt water(solution) to leave salt (the solute).


Have the students write brief explanations of (a)how the water cycle maintains a constant sealevel and (b) why ocean water is called a solution(and also a mixture). Call on volunteers to readtheir descriptions to the class.

Homework Assignment



Aim: What is the composition of oceanwater?



1. Draw a diagram of the water molecule.

2. Explain how salt dissolves in water.

3. List four compounds found in sea salts.


Show the class a glass of ocean (salt) water.Describe a simple experiment to demonstrate thatocean water contains salt.


1. Show students the residue on an evaporationdish. Note that ocean water contains dissolvedsubstances.

WRITE THE AIM: What is the composition ofocean water? About 96.5 percent of ocean wateris freshwater. Dissolved substances, consistingmainly of salts, make up the remaining 3.5percent.

2. KEY QUESTION: What kinds of salts are foundin ocean water? The salts dissolved in oceanwater are called sea salts. Artificial ocean watercan be prepared by dissolving sea salts in tapwater. Sea salts include the compounds listedin Table 15-1 on page 368. Ordinary table salt,sodium chloride (NaCl) is the most commonof the sea salts. When table salt is added towater, the NaCl breaks up, or ionizes, to formcharged atoms called ions. In seawater, theNaCl compound ionizes to form the positivelycharged sodium ion (Na+) and the negativelycharged chloride ion (Cl–).

3. KEY QUESTION: How does salt dissolve in water?Before this question can be answered, the stu-dents need to know about the water molecule.The chemical, or molecular, formula for thewater molecule is H2O. A molecule is defined asthe smallest quantity of an element or com-pound. One water molecule, H2O, is com-posed of two atoms of hydrogen joined withone atom of oxygen. (See Figure 15-4 on page369.) The oxygen side of the water molecule


(which has more electrons) has a negativecharge, while the hydrogen side (which hasfewer electrons) has a positive charge. Salt dis-solves in water because the opposite chargeson the water molecules attract ions from thesalt. The sodium ions and chloride ions sepa-rate and become surrounded by the watermolecules.


Organize the class into groups of three to fourstudents, with each team writing a paragraph thatexplains how salt dissolves in water. Have onestudent from each group write their explanationon the board and another student read it aloudto the class.

Homework Assignment

Read pages 367–369. Answer Section Reviewquestion 1 on page 373. Draw and label a dia-gram of a water molecule to accompany youranswer.


Aim: What is known about the pH of oceanwater?



1. Define the term acid rain.

2. Describe the pH of ocean water.

3. Explain the buffering effect in ocean water.


Show students a glass of rainwater. Have studentsexplain in writing why (in certain regions) rain-

water has been harmful to some aquatic organ-isms, such as freshwater fish and frogs.


1. Some bodies of water can become acidic dueto acid rain, or acid precipitation. Acid rainforms when chemicals released by the burningof fossil fuels are absorbed by moisture in theair. The degree of acidity or alkalinity of a liq-uid is called its pH.

2. WRITE THE AIM: What is known about the pHof ocean water? The term pH means the powerof the hydrogen ion concentration. The pH ofa substance is measured on a scale from zero(most acidic) to 14 (most alkaline), called thepH scale. The pH of ocean water is, on average,about 8, making it slightly alkaline. (See thepH scale in Figure 15-9, on page 370.)

3. KEY QUESTION: Why is ocean water slightlyalkaline? A small number of water moleculesdissociate into positive ions and negative ions.The ion with the positive charge is the hydro-gen ion (H+) and the ion with the negativecharge is called the hydroxyl ion (OH–). A solu-tion that contains a large number of hydrogenions is an acid. A solution that contains a largenumber of hydroxyl ions is a base, or alkalinesolution. If a substance contains an equalnumber of hydrogen and hydroxyl ions it iscalled neutral. Ocean water is slightly alkalinebecause the hydroxyl ions outnumber thehydrogen ions.

4. KEY QUESTION: Why is acid rain less of a prob-lem in the ocean than it is in a pond or lake?Chemicals in ocean water, called buffers, helpto maintain a stable pH. A buffer is a substancethat lessens the tendency of a solution tobecome too acidic or too basic. One of thebuffers in ocean water is the carbonate buffer(CO3

–). The buffering action in ocean watercan be seen in the following reaction (whichgoes to the left in ocean water): CO2 + H2O →H2CO3 → HCO3

– + H+ → CO32– + 2H+

5. The carbonate buffer can absorb hydrogenions from acid rain, thus maintaining a stable


pH of 8. Another reason that acid rain is not aserious problem in the ocean is because of theocean’s vast size. The large volume of oceanwater helps to dilutes the acid rain.


Organize the class into groups of three to fourstudents. Have students answer the two key ques-tions in paragraph form. Ask two students towrite their explanation on the board (one keyquestion each), and have another student readthem aloud to the class.

Homework Assignment

Read pages 369–372 (top). Answer Section Reviewquestion 2 on page 373, and Chapter Reviewquestions 9–11 on page 381.


Aim: What is known about molecular oxy-gen and its distribution in the ocean?



1. Write the word equation for photosynthesis.

2. Explain the origin and importance of DO inthe ocean.

3. Describe the relationship between DO anddepth.


Tell students to take a deep breath. Ask students:What important substance is entering your lungs?Where does it originate? Explain.


1. In order to survive, we need to breathe in air.The air contains molecules of oxygen, or O2,

the gas produced by algae and plants. Marineanimals need oxygen to survive, too.

2. WRITE THE AIM: What is known about molecu-lar oxygen and its distribution in the ocean? Mostof the oxygen in the ocean comes from algaeand other aquatic plants that live in the seaand along the shore. The process by whichgreen plants produce food and oxygen iscalled photosynthesis.

3. Write on the board the formula equation andword equation for photosynthesis. Call on astudent to read the equation aloud to theclass: six molecules of carbon dioxide, plustwelve molecules of water, in the presence oflight and chlorophyll, yield one molecule ofglucose, plus six molecules of water, plus sixmolecules of oxygen.

4. KEY QUESTION: How does the oxygen enter thewater? After oxygen leaves the aquatic algae,some enters the atmosphere and some dis-solves in the seawater. Molecular oxygen thatenters ocean water is called dissolved oxygen(DO); and the amount of O2 dissolved in thewater is expressed in units of parts per million(ppm) or milligrams per liter (mg/L). Oceanwater can hold from 1 ppm to 12 ppm of dis-solved oxygen. (In contrast, the amount of O2

in the air is about 200 ppm.)

5. KEY QUESTION: How is dissolved oxygen dis-tributed in the ocean? As depth increases, theDO decreases down to a depth of about 1000meters. The lowest amount of oxygen (inppm), called the O2 minimum zone, is found at1000 meters, not at the ocean bottom. Most ofthe oxygen is produced in the sunlit (photic)zone near the surface, where algae are found.In the depths, where it is too dark, no photo-synthesis occurs. However, the ocean is notcalm; waves and currents circulate oxygen tothe depths.


Organize the class into groups of three to fourstudents. Have the students write in their note-books the word equation for photosynthesis


along with a brief explanation of the origins ofDO in ocean water. Have a student from eachgroup write their information on the board andthen read it aloud. Compare and discuss theexplanations.

Homework Assignment

Read pages 372–373. Answer Section Reviewquestion 3 on page 373, and Chapter Reviewquestions 6 on page 380 and 14–19 on page 382.

LESSON 6 (pages 48–50, 373–374)

Aim: What do we know about the densityand salinity of ocean water?

Instructional Objectives:


1. Define density and salinity (of water).

2. Explain how to measure density and salinity.

3. Convert density units into percent salt values.


Ask students: Is it easier to float in a lake or in theocean? Explain.


1. Floating in the ocean is easier than floating ina lake because the ocean contains salt. Theamount of salt dissolved in ocean water iscalled its salinity. Salt increases the density ofwater. Density is defined as mass per unit vol-ume. The denser ocean water can support yourbody’s weight better than freshwater can.

2. WRITE THE AIM: What do we know about thedensity and salinity of ocean water? The densityof a liquid can be measured by using an instru-ment called a hydrometer. The hydrometer isan air-filled glass tube that has a weight at its

bottom, to keep it floating upright in a liquid.When hydrometers are placed in graduatedcylinders of freshwater and salt water, theycome to rest at different levels. (Refer studentsto Figure 2-12 on page 49.) The hydrometer inocean water floats higher in the cylinder thandoes the hydrometer in freshwater.

3. The density of a liquid can be measured byreading the scale inside the hydrometer. Thenumbers on the scale represent the range ofdensities of water. The hydrometer reading fordistilled water (pure freshwater) is 1.000. Thevalue of 1.000 represents the density, or spe-cific gravity, of distilled water. Specific gravityis defined as the ratio of the density of a sub-stance to the density of distilled water. Thehydrometer in the freshwater rests at 1.000.The hydrometer in the ocean water rests at1.0250.

4. KEY QUESTION: How is salinity measured? Sincethe greater density of ocean water is almostentirely due to the presence of salt, densityand salinity are often used interchangeably.However, salinity is expressed in percent. Theaverage salinity of the ocean is about 3.5 per-cent. Salinity is also expressed in parts perthousand (ppt). A salinity of 3.5 percent isequivalent to 35 ppt, also written as 350⁄00.Since salinity is given in percents, and thehydrometer uses specific gravity units, a con-version table is needed to find the percent salt.

5. Suppose the hydrometer in your aquarium hasa reading of 1.030. What would be the salin-ity of the water? As you can see in Table 2-4on page 50, the salinity would be 42 ppt, or4.2 percent. A salinity of 4.2 percent is highfor a saltwater aquarium.


Ask students: How can you lower the aquariumwater’s salinity to the recommended 3.5 percent (35ppt)? Also, have students explain why leaving thecover off a saltwater tank would lead to anincrease in salinity.


Homework Assignment

Read pages 48–50 and 373 (bottom)–374. AnswerSection Review questions 2–3 on page 51, andChapter Review questions 7 on page 57 and 17–18 on page 59.


Aim: How does salinity vary in the ocean?



1. Interpret an ocean salinity chart.

2. Describe how salinity varies in the ocean.

3. Explain why salinity varies in the ocean.


The water salinity under the Verrazano Bridge isslightly greater than the water salinity under theGeorge Washington Bridge. Point out the bridgeson a map of New York City, and elicit from stu-dents a possible explanation for this difference.


1. The Verrazano Bridge is situated closer to theocean, whereas the George Washington Bridgeis located farther upriver. Therefore, there ismore freshwater (and a lower salinity) underthe George Washington Bridge.

2. WRITE THE AIM: How does salinity vary in theocean? Project on the wall or draw on theboard a copy of the graph in Figure 15-10 (onpage 376). Note that the salinity at the bottomof the ocean is greater than at the surface.Salinity varies with depth; however, thechange is not uniform. A layer of water calledthe halocline, located between 100 and 200meters deep, shows a rapid change (i.e.,increase) in salinity.

3. KEY QUESTION: Why does salinity increase withdepth? Water is much colder deep in the oceanthan closer to the surface. In cold water, mole-cules and salt ions move closer together, thus

increasing the salinity. (In warmer surfacewaters, the salt ions are farther apart.)

4. KEY QUESTION: How does salinity vary on theocean surface? Distribute copies of Figure 15-8on page 375, or have students turn to thatpage in their textbooks. Lines on the map con-nect places of equal salinity. Draw twocolumns on the board, labeled GeographicRegion and Surface Salinity (ppt). Organize theclass into groups of four to five students andhave them determine the salinities for the fol-lowing regions: equator, 20 degrees N latitude,20 degrees S latitude, south polar region,north polar region, 40 degrees N latitude, 40degrees S latitude, and (approximate) middleof the Pacific Ocean. Record the data in theappropriate columns on the board. Have stu-dents copy the table into their notebooks.

5. KEY QUESTION: Based on your observations,what factors do you think affect the salinity ofocean water? Have the students in each groupwork together to answer this key question.


Have a student from each team write their answeron the board and then read it aloud. The follow-ing points should be mentioned.

■ Latitude: The highest salinities are recorded at20 degrees N and 20 degrees S, because thoseregions have more evaporation and less pre-cipitation. Salinity is lower at the equator, dueto high levels of precipitation.

■ Proximity to land: Water along the shore oftenhas a lower salinity than that of the openocean, due to freshwater runoff from the landand rivers.

■ Depth: As depth increases, the salinityincreases, due to cold water holding more saltions.

Homework Assignment

Read pages 374 (bottom)–377. Draw in your note-book a copy of Figure 15-10 (salinity/depthgraph) on page 376. Answer Section Review ques-tions 1–3 on page 377, and Chapter Reviewquestions 7 on page 380 and 22 on page 382.


Chapter 16/Geology of the Ocean

INTRODUCTION

In Chapter 16, students will learn about the formation of the oceans and continents, and about the geologicforces that have shaped, and continue to shape, the oceans and oceanic landforms. The interaction of land andsea is an ongoing process. Such geologic processes affect the characteristics of marine environments and theorganisms living in them.

■ Most of Earth is covered by water. The oceans surround the continents that formed as a result of the break-up of Pangaea.

■ The theory of plate tectonics explains the mid-ocean ridge, seafloor spreading, and continental drift.

■ Islands, coastlines, and reef structures all form as a result of geologic processes.

■ Sonar is used to learn about ocean-floor topography.

LESSON 1 (pages 385-390)

Aim: How can we explain the formation ofthe oceans and continents?



1. Discuss the conditions on early Earth.

2. Explain where the oceans came from.

3. Describe the theory of continental drift.


Show the class a map or globe of Earth. Ask stu-dents: Where did the oceans and continents comefrom? Explain.


1. Earth was born from a molten mass thatslowly cooled, producing gases, one of whichwas water vapor. The water vapor condensedinto rain, which filled depressions on Earth’ssurface, eventually forming the oceans. Someof the ocean water also came from Earth’s

crust, in the form of water-containing com-pounds, called hydrated compounds, such ascopper sulfate (CuSO4•5 H2O), which gives offwater when it is heated.

2. WRITE THE AIM: How can we explain the for-mation of the oceans and continents? Display onthe overhead a copy of Figure 15-3 (or havestudents look at it in the text, on page 389),which illustrates continental drift. More than200 million years ago, all the continentsexisted as a single supercontinent (surroundedby ocean), which scientists call Pangaea. Overtime, Pangaea broke into several smaller con-tinents that drifted apart, eventually attainingthe shapes and positions that they occupytoday. This idea of the break-up and separa-tion of landmasses over time is called the the-ory of continental drift and was first proposedby the German meteorologist Alfred Wegenerin 1912. Wegener was actually ridiculed byother scientists at that time, since he couldnot explain how drift occurred.

3. KEY QUESTION: What powerful forces caused the landmasses to split apart? Show diagram ofEarth’s interior. (See Figure 16-4 on page 389.)The interior layers consist of the inner core,outer core, and mantle. The molten rock mate-rial in the mantle, called magma, ranges intemperature from 1200°C to 5000°C. Power-ful, upward forces generated by these high


temperatures in the magma caused the outerlayer, or crust, to crack.

4. KEY QUESTION: What is the effect of these pow-erful forces on Earth’s crust? When the crustcracks, the ground above it moves, producingearthquakes (or seaquakes, if they occur on theocean floor). If the opening is big enough,magma may flow out as lava, producing a vol-canic eruption. Disturbances in Earth’s crust,such as volcanic eruptions and earthquakes,are examples of seismic activity. On a globalscale, when large sections of crust have brokenapart, they float on the molten mantle (whichmoves below them), causing continental drift.


Organize the class into groups of three to fourstudents, with each team preparing a briefsummary of the lesson. Call on a volunteer toread aloud their group’s summary statement tothe class. Encourage discussion about this once-controversial topic.

Homework Assignment

Read pages 384–390 (top). Answer Section Reviewquestions 1–3 on page 390, and Chapter Reviewquestion 6 on page 412.


Aim: How can we describe the movements ofEarth’s crust?



1. Define the process of plate tectonics.

2. Identify Earth’s major crustal plates.

3. Explain why the Atlantic Ocean widens eachyear.


Show the class a world map. Mention that theAtlantic Ocean widens by a few centimeters eachyear. Explain.


1. The Atlantic Ocean gets slightly wider eachyear because the continents are still movingapart.

2. WRITE THE AIM: How can we describe the move-ments of Earth’s crust? Earth’s crust is dividedinto floating segments called plates. Project onthe overhead the crustal plates. (Refer to Fig-ure 16-5 on page 391.)

3. Organize the class into groups of three to fourstudents. Hand out sheets of paper (81⁄2 ✕ 14)to each group. Have the students draw theplates on the paper, cut the plates out, thenmix them up and put them back together likethe pieces of a jigsaw puzzle.

4. KEY QUESTION: How many plates are there andwhat are their names? Count the plates and listtheir names on the board. There are ninemajor plates: Pacific, North American, Nazca,South American, Eurasian, Arabian, African,Indian, and Antarctic. Students should copythese names onto their plates, and paste thereassembled set into their notebooks.

5. KEY QUESTION: How (i.e., in what direction) dothe plates move? Place your left index fingerand thumb on the North American and SouthAmerican plates. Place your right index fingerand thumb on the Eurasian, Arabian, andAfrican Plates. Move the two sets of platesaway from each other (i.e., in the direction ofthe arrows, as shown in Figure 16-5). The the-ory of plate tectonics describes the process bywhich Earth’s crust breaks into plates and howthe plates move (due to activity in the man-tle) in their specific directions.



Have students in each group define the process ofplate tectonics. Call on a volunteer from eachgroup to read their definition to the class.

Homework Assignment

Read pages 390–391. Answer Section Reviewquestion 1 on page 394. Students should finishlabeling and reassembling in their notebooks thecopies of Earth’s crustal plates.

LESSON 3 (391–394)

Aim: How can we explain the movement ofEarth’s crust?



1. Cite examples of seismic activity.

2. Explain how oceanic ridges are formed.

3. Describe the process of subduction.


Sketch on the board a picture of the Mid-AtlanticRidge. Explain how this underwater “mountainrange” originated.


1. Mountain formation, earthquakes, volcaniceruptions are examples of seismic activity. Seis-mic activity is evidence that Earth’s crust ismoving.

2. WRITE THE AIM: How can we explain the move-ment of Earth’s crust? Project on the overhead acopy of Figure 16-6 (on page 359). The crustmoves as a result of high temperatures gener-ated in the mantle. The big difference in tem-perature between the upper mantle and thelower mantle creates the convection currents,

which cause the magma to rise up through themantle and into the crust.

3. KEY QUESTION: How is the Mid-Atlantic Ridgeformed? The upward movement of magma intothe crust produces the Mid-Atlantic Ridge, amountain range that runs the entire length ofthe Atlantic Ocean. This flow of magmathrough the crust also causes seafloor spread-ing—the process that is moving apart the(oceanic) crustal plates.

4. KEY QUESTION: How are the trenches formed?A trench is the geological feature found in the deepest parts of the ocean. Trenches format the margins of plates. When plates collideas a result of seafloor spreading, one plateplunges downward below the other plate, inthe process called subduction. The area atwhich this occurs forms the trench. The deep-est trench, at nearly 11,000 meters, is the Mar-iana Trench in the Western Pacific Ocean.


Have students work in groups to explain the fol-lowing seismic activities: seafloor spreading, ridgeformation, and subduction/trench formation.Have a student from each team read their descrip-tions to the class.

Homework Assignment

Read pages 392–394. Answer Section Reviewquestions 2–3 on page 394, and Chapter Reviewquestions 9–11 and 15–16 on pages 412–413.


Aim: How is sonar used to learn about theocean floor?



1. Define sonar.


2. Explain how sonar works.

3. Describe how depth is calculated.


Draw a diagram of an undersea trench on theboard. Ask how scientists know that the MarianaTrench is nearly 11,000 meters deep.


1. Oceanographers use sonar, an acronym forsound navigation and ranging, to measureocean depth. Sonar is also used to determinewhat features are found on the ocean floor.The study of Earth’s features on land and onthe ocean floor is called topography.

2. WRITE THE AIM: How is sonar used to learnabout the ocean floor? Project on the overhead acopy of Figure 16-11 (on page 395). Modernships are equipped with sonar. A ship’s sonardevice beams a continuous signal downward.After the sound wave hits the bottom, thereturning signal, or echo, is received by a depthrecorder in the ship. This produces a line trac-ing of the ocean floor (as shown in the bottomdiagram). Ocean depth is calculated by know-ing the speed of sound in water (1454 meters/second) and the time it takes for the signal toreach the bottom. The following formula isused to calculate the depth: Depth (D) = 1454meters/second ✕ time (t) ÷ 2.

3. KEY QUESTION: How deep is the ocean if a signaltakes one second to return to the ship after beingsent? Have a student work out the problem onthe board. Substituting into the formula wehave: D = 1454 m/second ✕ 1 second ÷ 2; D =1454 m ✕ 1⁄2; D = 727 meters.

4. KEY QUESTION: How deep is the ocean if a signaltakes one-half second to return? Have the classwork out this problem; then call on a studentto write it on the board, as follows: D = 1454m/second ✕ 0.5 second ÷ 2; D = 1454 m/sec-ond ✕ 0.25; D = 363.5 meters.


Have students work in groups to determine oceandepth in various assigned problems. Call on vol-unteers to do the problems on the board andexplain their answers to the class.

Homework Assignment

Read pages 395–396. Answer Section Reviewquestion 1 on page 404.

LESSON 5 (pages 397–399, 401–404)

Aim: How can we describe the topographicalfeatures found on the ocean floor?



1. Identify various seafloor features.

2. Describe the topographical features.

3. Explain how these features are formed.


Display a topographical map of the ocean floor.Point out and describe several features.


1. There are two ways to observe topographicalfeatures: from above and from the side (profileview). Both views are useful in determiningwhat the ocean floor looks like.

2. WRITE THE AIM: How can we describe the topo-graphical features found on the ocean floor? Pro-ject on the overhead a profile (or side view) ofseafloor topographical features. (See Figure16-12 on page 396.) Have students copy thisprofile into their notebooks.

3. KEY QUESTION: What do we know about thesetopographical features? Organize the class intoeight groups of students, with each teamresearching and writing about a different topo-graphical feature. Information on the features


can be found on the following pages: conti-nental slope (397), submarine canyon (397–398), continental rise (398), seamount (398–399), guyot (399), trench (399), island arc(401), and mid-ocean ridge (401–402).

4. The following are some facts that you maywant to see mentioned:

■ Continental slope: is the area where theseafloor drops steeply; located at the outeredge of the continental shelf.

■ Submarine canyon: is a steep V-shapeddepression that cuts through the continen-tal shelf; is an extension of a sunken rivervalley.

■ Continental rise: is the slightly elevatedregion that forms at the base of a conti-nental slope from the accumulation ofmudslide sediments.

■ Seamount: is a small undersea mountainformed by lava piling up on the seafloor;forms over hot spots in the mantle; theHawaiian Islands are actually a chain ofseamounts.

■ Guyot: is a flattened undersea structureformed when waves and currents erode thetop of a seamount.

■ Trench: is a steep, deep V-shaped depressionon the seafloor; found at margins of crustalplates (in subduction zones); is the deepestfeature on the ocean floor.

■ Island arc: is a group of islands that formsan arc in the ocean; many are volcanicallyactive; associated with trenches.

■ Mid-ocean ridge: is an undersea volcanicmountain range that encircles the globe;along its crest is the rift valley, throughwhich molten rock from the mantle isexpelled; the rift zone also containshydrothermal vents from which hot min-eral-laden waters emerge.


Call on eight students to come up to the board(one at a time) to sketch and describe one topo-

graphical feature from the list you gave them.Have another student from each group write abrief description on the board.

Homework Assignment

Read pages 397–399, 401–404 (top). Answer Sec-tion Review questions 2–3 on page 404.


Aim: How can we describe shoreline topog-raphy?



1. Identify various shoreline features.

2. Describe how shoreline features develop.

3. Explain how a coral reef evolves.


Have students write a physical description of abeach that they have visited. (For landlockedareas, students can describe lakeshore beaches.)


1. Approximately 70 percent of the U.S. popula-tion lives within 80 km of a coast. The coast,or shore, is the boundary between land andsea. Shorelines are composed of different kindsof substrates. Some coasts, like Maine and Ore-gon, are rocky, while others, like Florida, havesandy beaches. Some tropical islands haveshorelines made up of coral.

2. WRITE THE AIM: How can we describe shorelinetopography? Organize the class into groups ofthree to four students, with each teamresearching a different shoreline feature. Infor-mation on the different shoreline (coastal) fea-tures can be found on the following pages:sandy beach (404–405), delta (405–406), rocky


coast (404, 406–407), fjord (407), fringing reef(408), barrier reef (408), key/cay (409), andcoral atoll (409).

■ Sandy beach: has loose sediments or sanderoded by waves from rocks along theshore, or from rocks eroded from moun-tains and transported by rivers down to theshore.

■ Delta: is a fan-shaped deposit of sedimentsthat piles up at the mouth of a large riverwhere it enters a calm ocean.

■ Rocky coast: is usually a very steep shorelineformed by the carving action of glaciers.

■ Fjord: is a steep, deep narrow inlet from thesea formed by the action of glaciers.

■ Fringing reef: is a reef that grows a few kilo-meters offshore, parallel to the mainland.

■ Barrier reef: is a coral reef that grows farther(25 km) offshore than a fringing reef.

■ Key (Cay): is a small island that forms whenchunks of coral stone break off from a reef

and accumulate on the seafloor; e.g., theFlorida Keys and the Cayman Islands.

■ Coral atoll: is a string of islands that forms acircle (around a lagoon); represents thefinal stage in reef evolution (around asunken volcanic island); e.g., Midway andEniwetok.


Have a volunteer from each group describe theirshoreline feature and write a brief description onthe board. Have another student volunteer todraw the feature on the board. Students shouldcopy the completed descriptions into their note-books.

Homework Assignment

Read pages 404 (bottom)–409. Answer SectionReview questions 1–3 on page 409.

Chapter 17/Climate and the Ocean

INTRODUCTION

In Chapter 17, students will learn how the ocean exerts a great influence on Earth’s weather and climate. Theinteraction of air, water, and land—and, particularly, the cycling of water through these layers—determineslocal weather conditions and global climate patterns. The impact of El Niño events on marine animals and onhumans and the impact of humans on global warming trends are also explored.

■ Ocean temperatures depend on the heating of Earth’s surface by the sun. The ocean is warmest at theequator, coldest at the poles.

■ The ocean heats more slowly and retains heat longer than land does. This leads to formation of sea breezesand land breezes.

■ Humidity is the amount of moisture in the air. Fogs, dew, and hurricanes all form as a result of temperaturedifferences (in air and water) and levels of moisture in the air.

■ El Niño events are caused by a warm ocean current in the Pacific; they affect global weather patterns anddisrupt local fisheries.

■ The greenhouse effect (and global warming) results from the trapping of heat in Earth’s atmosphere by car-bon dioxide and water vapor. Burning of fossil fuels may have caused this trend, which has led to increasedmelting of polar ice caps and a subsequent rise in sea level.



Aim: How can we explain variations in oceansurface temperatures?



1. Define angle of isolation and explain itsimportance.

2. Explain why ocean temperature varies withlatitude.

3. Describe how Earth’s tilt causes seasonalchanges in ocean temperature.


Show the class a globe or map of Earth. Ask stu-dents where they think the warmest land andocean surfaces are, and where the coldest land andocean surfaces are. Explain.


1. Temperature is a measure of the average kineticenergy of a substance. Parts of the ocean sur-face vary in temperature based on latitudeand/or based on the time of year (season).

2. WRITE THE AIM: How can we explain variationsin ocean surface temperatures? Energy from thesun (radiant energy) that reaches Earth’s surfacemay be reflected or absorbed. Some of theabsorbed energy is transferred into heat. Theamount of energy absorbed depends on theangle at which the sun’s rays strike Earth’s sur-face, called the angle of insolation. The surfacetemperature of the ocean varies according tolatitude (the distance north and south of theequator), due to the differences in the angle ofinsolation. Refer students to the diagram inFigure 17-2 on page 417, which illustrates thiseffect.

3. KEY QUESTION: Why does ocean temperaturevary with the seasons? Ocean temperature alsovaries by season as a result of the inclination

of Earth’s axis 231⁄2 degrees. Project on theboard Figure 17-3 on page 418. Have studentscopy the diagram into their notebooks.Explain how Earth’s tilt affects where andwhen the sun’s direct rays strike Earth.


Organize students into groups to consider the fol-lowing question: How does the angle of insolation,and the tilt of Earth’s axis, determine ocean surfacetemperature differences? Have a student from eachgroup read their answer to the class.

Homework Assignment

Read pages 415–419 (top). Answer Section Reviewquestions 1–2 on page 421, and Chapter Reviewquestions 6 on page 436 and 9–11 on page 437.


Aim: Why is it windy along the coast?



1. Define convection currents (in water and inair).

2. Explain how convection currents cause winds.

3. Distinguish between a sea breeze and a landbreeze.


Describe some weather conditions on a day at thebeach.


1. The conditions in the atmosphere, such astemperature, moisture, and wind velocity, arecalled weather conditions. Weather will varyfrom place to place, but over a large geograph-ical area there is an average or prevailing pat-tern of weather called climate. One common


weather condition along coastlines is thewind.

2. WRITE THE AIM: Why is it windy along thecoast? The wind is a mass of moving air. Airmoves when there is a difference in tempera-ture between adjoining air masses. Alongcoasts, there is a difference in air temperatureover the land and over the ocean.

3. Set up the smoking chimney demonstrationillustrated in Figure 17-5 on page 420, or referstudents to the diagram in their textbook.

KEY QUESTION: Why does smoke go down onechimney and go up the other chimney? Explana-tion: Smoke goes down one chimney and upthe other one because air warmed by the can-dle rises, and the cooler air entering the otherchimney sinks (along with the smoke) to takeits place. These movements of air, caused by adifference in temperature, are called convectioncurrents.

4. KEY QUESTION: How can we explain the breezesthat occur along the coast? A gentle wind iscalled a breeze. There are two kinds of breezesthat occur along the shore: a sea breeze and aland breeze. (Refer students to Figure 17-4 onpage 419.) Explanation: During the day, theland heats up more quickly than the waterdoes. The hot air above the beach rises, andthe cooler air above the ocean flows landward,producing a sea breeze. At night, the oppositeoccurs. The air over the ocean is warmerbecause water holds heat longer than landdoes. The warmer air over the ocean rises, andthe cooler air above the land flows seaward totake its place, producing a land breeze. Theseare examples of convection currents (in theair).


Have students work in groups to explain, in writ-ing, why land and sea breezes occur along thecoast. Have a student from each group read theirexplanation to the class.

Homework Assignment

Read pages 419–421. Answer Section Reviewquestion 3 on page 421, and Chapter Reviewquestions 12, 14, and 17 on pages 437–438.


Aim: Why is it foggy along the coast?



1. Distinguish between the dew and a fog.

2. Explain how a fog is produced.

3. Describe fog formation in different localities.


Take a glass of ice water from a refrigerator andplace it on your desk. Ask students to write theirobservations and try to explain what they see.


1. A glass of cold water appears to “sweat” whenplaced in a warm room. The moisture on theoutside of the glass comes from the air. Whenwater vapor in the air makes contact with acold surface, it condenses (changes from vaporto liquid) to form moisture called dew. Warmair that is saturated with moisture near the(cooler) ground is called fog.

2. WRITE THE AIM: Why is it foggy along thecoast? The temperature at which water vaporcondenses as a cloud or fog is called dew point.Coastal fog forms at the surface of the oceanwhen the dew point is reached; i.e., the coldsurface water cools the warm, moist air aboveit to the point at which the air cannot hold allthe water vapor.

3. KEY QUESTION: How can we explain fog in dif-ferent parts of the world? Describe the followinginstances of fog formation on coastlines:


■ San Francisco fog: occurs when the cold Cal-ifornia Current moving south along thecoast meets the warm, moist air carried inby the prevailing westerly winds; the coldwater cools the moist air above it to thepoint at which the excess water vaporforms a fog.

■ London fog: occurs when the warm GulfStream reaches the coast of Great Britain;the warm, moist air above the currentmeets the cool land surface of England,forming a fog.

■ Newfoundland fog: occurs when the warmGulf Stream (heading north) meets the coldLabrador Current (heading south), causingcondensation into a thick fog; this coast isthe foggiest place in the world, averagingabout 120 foggy days each year.


Have students work in groups to explain how fogforms in different localities. They can use a map(showing currents) as a guide. Ask volunteers toread their explanations to the class.

Homework Assignment

Read pages 422–424. Answer Section Reviewquestions 1–3 on page 424, and Chapter Reviewquestions 13 and 16 on page 438.


Aim: How can we explain stormy weatheralong the coast?



1. Discuss the dynamics of a hurricane.

2. Explain why hurricanes are less destructivetoday.

3. Describe El Niño (and La Niña) currents.


Ask the students if they have ever experienced ahurricane or some other stormy weather. Havethem describe their experience.


1. Two of the most destructive climate eventsthat can occur along coastlines are hurricanesand El Niño currents. A hurricane is a coastalstorm that has a wind velocity of more than120 km per hour.

2. WRITE THE AIM: How can we explain stormyweather along the coast? Hurricanes develop intropical seas where warm, moist air containsthe heat needed to fuel the storm. As the hot,moist air rises, it forms a whirlwind of air thatmoves up in a spiral direction around a coreof calm air, known as the eye. Hurricane inten-sity is rated on a scale from one to five, calledthe Saffir-Simpson Damage Potential Scale. Acategory-one hurricane causes “minimal”damage, while a category-five (with windsover 250 km per hour) causes “catastrophic”damage. Hurricanes lose their intensity as theymove inland due to the lack of moisture; andthey lose intensity as they move over coolerwaters due to the lack of sufficient heat.

3. KEY QUESTION: Why have fewer people died inhurricanes in recent years (than in previousdecades)? Fewer people die as a result of hurri-canes nowadays because of the developmentof early warning systems provided by theNational Hurricane Center in Florida and fed-eral agencies such as NOAA (which fly into thestorms and monitor them continuously).

4. KEY QUESTION: How can we explain the manyclimate-related disturbances that have occurred in recent years? An unpredictable current ofwarm water, called El Niño, which flows east-ward across the equatorial Pacific (when thetrade winds weaken), is considered responsiblefor disrupted fisheries off South America,floods and stormy weather in North America,


droughts in Australia, and even famine inAfrica.


Climate events that result from the interplay ofoceanic and atmospheric forces have a greatimpact on coastal communities of marine ani-mals and humans. Have students write in theirnotebooks brief definitions for hurricane, stormsurge, El Niño, and La Niña. Read to class.

Homework Assignment

Read pages 424 (bottom)–429. Answer SectionReview questions 1–3 on page 429, and ChapterReview questions 15, 20, and 21 on page 438.


Aim: How can we explain Earth’s currentwarming trend?



1. Define the greenhouse effect.

2. Explain causes of the greenhouse effect.

3. Discuss implications of the warming trend.


Have students copy into their notebooks thegraphs in Figure 17-17 on page 432. Ask them towrite a conclusion based on a comparison of thedata in both graphs.


1. The planet’s mean global temperature hasincreased 1 degree Celsius (1°C) over the past100 years.

WRITE THE AIM: How can we explain Earth’scurrent warming trend? Examine the twographs, one of which shows the atmosphericwarming trend, and the other which showsthe rising sea level. It is thought that thiswarming trend, commonly called global warm-ing, has caused some melting of the polar icecaps and the subsequent rise in the sea level.

2. KEY QUESTION: What is causing this warmingtrend? Carbon dioxide (CO2) is called a green-house gas because it traps heat in the atmos-phere in much the same way that glass wallstrap infrared heat within a greenhouse. Theheating of the atmosphere as a result of theaccumulation of greenhouse gases is called thegreenhouse effect. (Refer to Figure 17-16 on page430, and Figure 17-18 on page 433.)

3. KEY QUESTION: How does CO2 accumulate inthe atmosphere? Much of the CO2 accumulatedin our atmosphere as a result of the burningof fossil fuels, such as coal, oil, and gas,brought on by the Industrial Revolution,which began over 100 years ago. Some scien-tists claim that the current warming trend ispart of a natural cycle that will eventuallyreverse itself through CO2 uptake by photo-synthetic plants and algae.


Organize the class into several groups, with eachteam presenting a written argument for or againstthe notion that global warming is taking place.Have volunteers present their arguments (andsupporting evidence from the textbook) to theclass.

Homework Assignment

Read pages 430–433. Answer Section Reviewquestions 1–3 on page 433, and Chapter Reviewquestions 8 on page 436 and 22 on page 439.

73

UNIT 6 ENERGY IN THE OCEAN

Chapter 18/Temperature and Pressure

INTRODUCTION

In the previous chapter, students learned about the interaction of ocean surface temperatures and the atmos-phere. In Chapter 18, they will learn about variations in ocean temperature, from the surface to the seafloor,and about its impact on marine organisms. Animals have a variety of adaptations that enable them to survivein cold waters. Water pressure also has a great impact on the lives of marine creatures. Animals have evolvedways to withstand the crushing pressures of the ocean depths. Also discussed is how aquatic animals have toregulate their water balance with regard to osmotic pressure.

■ Temperature differences affect water density. The temperature of the ocean varies (generally decreasing)with depth.

■ Colder water temperatures decrease metabolic activity. Marine creatures have special adaptations for livingin cold waters.

■ The water’s mass exerts hydrostatic pressure. This underwater pressure, along with the atmospheric pres-sure above it, is called ambient pressure, which increases at regular intervals with depth.

■ Marine animals have special features that enable them to withstand differences in pressure underwaterand to adjust to the effects of deep-sea pressure.


Aim: How does temperature affect thechange in state of ocean water?



1. Identify water in its different states.

2. Explain why water changes its state.

3. Describe changes in state in different parts ofthe ocean.


Display to students an evaporating dish fromwhich ocean water has evaporated, and some ice

in a tray. Describe changes in state that occur inwater.


1. When water evaporates, or when ice melts,there is change in state of the water that iscaused by a transfer of heat energy from onesubstance to another substance.

2. WRITE THE AIM: How does temperature affectthe change in state of ocean water? Temperatureis a measure of the amount of heat energy pos-sessed by a substance. Heat energy is the energypossessed by a substance as a result of the mol-ecular activity of that substance. Heat energyis measured in calories. A calorie is the amountof heat required to raise the temperature of


one gram of water one degree Celsius. Thetemperature in the ocean varies so much that(at certain times and in certain locations) thewater can exist in its three different phases, orstates, of matter: solid (ice), liquid (water), andgas (steam).

3. KEY QUESTION: How can we describe energytransfer during a change in state? The change forone gram of water to steam requires 540 calo-ries of heat (absorbed by the water), called theheat of vaporization. The change for one gramof water to ice (i.e., freezing) requires 80 calo-ries of heat (removed from the water), calledthe heat of fusion. (The melting of one gram ofice into water also requires 80 calories of heat.)(See Figure 18-1 on page 444.)

4. KEY QUESTION: Where in the ocean does achange of state occur? When water evaporatesfrom the ocean surface, there is a change ofstate from liquid to gas, and heat is releasedinto the atmosphere. On active volcanicislands like Hawaii, hot molten lava some-times flows into the ocean, causing it to boiland produce billowing clouds of steam. Whenwater on the ocean surface falls below thefreezing point, it changes into ice.

5. KEY QUESTION: What kinds of ice occur in theocean? There are two kinds of ice in the ocean:sea ice and icebergs. Sea ice is formed when thetemperature of water on the ocean surfacedrops below the freezing point (at about –2°C).An iceberg is a chunk of ice that breaks offfrom the end of a glacier and floats into theocean. Both can be hazards to navigation.


Divide the class into groups of three to five stu-dents. Have each group describe a change in state(for water) and give one example of it that occursin the marine environment.

Homework Assignment



Aim: What do we know about ocean tem-perature and its effect on living things?



1. Explain what the thermocline is.

2. Describe the relationship between temperatureand depth.

3. Discuss how marine animals are adapted tocold temperatures.


Draw the water column on the board. Ask stu-dents: Where (in the ocean’s water column) wouldthe temperature be warmer—closer to the surface orat the bottom? Explain.


1. Much of the sun’s radiant energy that pene-trates the ocean surface is absorbed in theupper layers and changed into heat. Since lessheat energy reaches the depths, the tempera-ture is much lower (colder) there. A variety ofmarine organisms have successfully adapted tothe differences in temperature throughout thewater column.

2. WRITE THE AIM: What do we know about oceantemperature and its effect on living things? Oceantemperature varies with depth. As depthincreases, water temperature decreases. But thedecrease is not uniform. There is a more rapiddrop in temperature between 200 and 1000meters, in a layer of water called the thermo-cline. Oceanographers get an accurate temper-ature profile of the ocean by using aninstrument called the bathythermograph.

3. KEY QUESTION: How do marine animals adjustto differences in temperature? In many marineanimals (including fish), when the temperatureof the environment changes, their internal

UNIT 6 / ENERGY IN THE OCEAN 75

body temperature also changes. Animals thathave a variable, or unstable, body temperatureare called ectothermic, or cold-blooded, animals.When the water temperature increases, theirenergy level or (metabolic activity) also in-creases. Cold-blooded animals can only live inenvironments that have narrow temperatureranges. If the temperature is not suitable, theymove to either warmer or cooler waters.

4. KEY QUESTION: How do organisms adapt toextremely cold environments? The icefish (of Arc-tic and Antarctic waters) has a natural “anti-freeze” chemical in its blood that prevents itstissues from freezing. (See illustration on page448.) Some warm-blooded, or endothermic, ani-mals such as whales and seals have a thick layerof fatty tissue (blubber) under the skin, whichhelps insulate against heat loss. Pinnipeds andother marine mammals also have thick fur.Humans are warm-blooded, but do not haveheat-retaining structures. Thus, exposure tocold water can lead to an excessive loss of bodyheat, which can cause a life-threatening condi-tion called hypothermia. If heat loss continues,the drop in body temperature can lead tounconsciousness. A person can restore theirnormal body temperature by getting out of thewater quickly, removing all wet clothing, andkeeping warm and dry.


Organize the class into groups of four to five stu-dents. Have each team pick a different animaldescribed in the chapter and answer ChapterReview question 6 on page 463 for that organism.

Homework Assignment



Aim: How is underwater pressure measured?



1. Explain why water has pressure.

2. Define units of pressure and units of force.

3. Calculate water pressure on the bottom of acontainer.


Fill with water a milk container in which youhave already cut and plugged three holes. (SeeFigure 18-5 on page 451.) Pull out the three plugs.From which hole (or holes) does the water spurtfarthest? Explain.


1. The water spurts farthest from the hole at thebottom of the container because there is morepressure at the bottom than at the top.

WRITE THE AIM: How is underwater pressuremeasured? The pressure is defined as a force (F)applied over a given area (A), and can be cal-culated by using the following formula: Pres-sure = force/area, or P = F/A, where pressure ismeasured in units called pascals. One pascal isequal to one newton of force per square meter(m2). The force (F), or weight, of an object isdefined as the product of its mass (m) timesacceleration (a), and can be calculated by usingthe following formula: F = ma, where accelera-tion due to gravity is 9.8 m/s2. Force is mea-sured in units called newtons.

2. KEY QUESTION: If the mass of water in a con-tainer is 0.5 kilograms (kg), what is the waterpressure (P) at the bottom of the container? Firstfind the force, using the formula F = ma:

F = (0.5 kilograms) (9.8m/s2); F = 4.9 newtons.

Substituting the 4.9 newtons force (F) into theformula for pressure (P), you have:

P = F/A; P = 4.9 newtons/A.

To find the area (A) at the base of the con-tainer, multiply the length, which is 100 mm(or 0.1 m) times the width, which is also 100mm (or 0.1 m), using the formula A = l ✕ w:


A = 0.1m ✕ 0.1m; A = 0.01 m2.

Substituting the 0.01-m2 area (A) into the for-mula for pressure (P), you have:

P = F/A; P = 4.9 newtons/0.01m2; P = 490 pascals.


Organize the class into groups of four students.Have them work on problems to calculate pres-sure. Vary the values for the size of the containerand/or magnitude of the water mass for eachteam. Have volunteers from each group come tothe board to write out the problems.

Homework Assignment

Read pages 451–453 (top). Review the units ofmeasurement for force (newtons) and for pressure(pascals), and the formulas for finding force (F),area (A), and pressure (P).


Aim: How does pressure vary with depth?


Student will be able to:

1. Define ambient pressure.

2. Describe the relationship between pressureand depth.

3. Explain why pressure varies with depth.


Draw on the board a picture of a diver underwa-ter and a person in a rowboat. Which person isunder greater pressure? Explain.


1. The diver is under greater pressure because thewater’s mass exerts more pressure than theatmosphere does.

WRITE THE AIM: How does pressure vary withdepth? The pressure exerted by a mass of wateris called hydrostatic pressure. The pressureexerted by air is called atmospheric pressure.Under normal conditions, the atmosphericpressure at sea level is equal to approximately101 kilopascals (kPa). For every 10 meters ofdepth, hydrostatic pressure increases by 101kPa (one atmosphere). The total pressure, orambient pressure, on a diver is the sum of theatmospheric pressure plus the hydrostaticpressure. Pressure can also be expressed inatmospheres, where one atmosphere equals 101kPa. (See Table 18-2 on page 453.)

2. KEY QUESTION: How can the relationship be-tween pressure and depth be described? The rela-tionship between pressure and depth is shownin Figure 18-6 on page 454. There is a directrelationship between depth and pressure. Asdepth increases at regular intervals, pressurealso increases at a uniform rate (and vice versa).

3. KEY QUESTION: What is the ambient pressure ona diver at a depth of 60 meters? The ambientpressure would be the sum of the atmosphericpressure (101.325 kPa) plus the hydrostaticpressure (607.950 kPa), which equals a total(ambient) pressure of 709.275 kPa.

4. KEY QUESTION: Why is there a pressure of oneatmosphere at zero depth (i.e., at the ocean sur-face)? Air exerts pressure on the ocean surfaceequal to one atmosphere (101.325 kPa).


Organize the class into groups of three to fourstudents. Have each team determine the ambientand hydrostatic pressures at seven differentdepths, going from 70 meters to 130 meters. Haveeach group leader write an answer on the boardand explain it to the class.

Homework Assignment

Read pages 453–454 (top). Answer Section Reviewquestion 1 on page 457, and Chapter Reviewquestions 14–16 on page 465.



Aim: Why does water pressure limit thedepth to which humans can descend?



1. Explain how ambient pressure affects humans.

2. Discuss the three kinds of barotraumas.

3. Describe how decompression illness occurs.


Why can’t humans explore deep-sea wrecks, suchas the Titanic, in scuba gear? Explain.


1. Pressure limits the depths to which humanscan descend. The Ama pearl divers of Japanhave the greatest endurance of any free divers;they can make repeated dives to 18 meters andstay down for one minute. The record for asingle free dive is about 105 meters, whereasthe record for scuba diving is 132 meters.

2. WRITE THE AIM: Why does water pressure limitthe depth to which humans can descend? As soonas a diver goes underwater, ambient pressureexerts a force over the entire surface of his orher body. The body’s thin membranes are thefirst to feel the effects of pressure.

3. KEY QUESTION: How does water pressure affectthe body’s membranes? Display a wall chart ormodel of the ear. Point to the eardrum (tym-panic membrane) and the sinus cavities in thefacial bones, which are lined with membranes.As a diver descends, pressure increases onthese membranes, causing discomfort or pain.Pain in the ear is called ear squeeze and pain inthe forehead is called sinus squeeze. This paincan be eliminated by equalizing the pressure,which is done by blowing through the nosewhile pinching the nostrils closed. When thediscomfort is eliminated, the diver can con-

tinue to descend. Ear squeeze and sinussqueeze are injuries that occur only when thediver descends. Any diving injury associatedwith pressure changes (on descent or ascent)is called a barotrauma.

4. KEY QUESTION: What kinds of injuries occurduring ascent? Coming up too quickly cancause a serious injury to scuba divers calledthe bends. If a diver ascends too quickly, thereis a sudden decrease in pressure. This decrease,called decompression, can cause gases to formbubbles in the tissues in the same way thatbubbles appear in a bottle of soda when it isopened. The gas bubbles accumulate in thejoints, causing the diver to bend over in pain.The bends is an example of a decompressionillness.

5. KEY QUESTION: Can a decompression illness befatal? Another decompression illness is calledan air embolism. This potentially fatal condi-tion occurs when gas bubbles develop insidethe blood vessels, blocking circulation to vitalorgans such as the heart or brain. To preventdecompression illness, scuba divers mustascend slowly, while breathing at a normalrate. Explain that decompression illness doesnot occur in snorkelers because they are notbreathing in compressed air. A diver can betreated for decompression illness by beingplaced inside a decompression chamber for sev-eral hours.

6. KEY QUESTION: What other factors limit thedepth to which divers can descend? Scuba diverswho make deep dives below 30 meters mayexperience nitrogen narcosis, a condition thatresembles alcohol intoxication. The diverappears drunk and is not able to carry out sim-ple tasks, a threat to the diver’s safety. Nitro-gen narcosis results from breathing nitrogengas (N2) under pressure from a compressed airtank. Removing nitrogen and adding heliumreduces the incidence of nitrogen narcosis.


Organize the class into four or five groups. Haveeach team research (in their textbook) and write


about one type of barotrauma or diving illness.Have each group leader write their brief descrip-tion on the board. Encourage discussion.

Homework Assignment



Aim: How do aquatic organisms maintain aproper water balance?



1. Define osmoregulation.

2. Describe how the process of osmosis occurs.

3. Explain why some aquatic organisms are poorosmoregulators.


If a goldfish is accidentally placed in a saltwatertank, it will die. Likewise, if a sea star is acciden-tally placed in a freshwater tank, it will die.Explain.


1. The goldfish would die because, in a saltwatertank, it would lose too much water from itsbody. The sea star would die because, in afreshwater tank, it would gain too much waterfrom the environment.

2. WRITE THE AIM: How do aquatic organismsmaintain a proper water balance? The ability ofan aquatic organism to maintain a proper(internal) water balance is called osmoregula-tion. This ability depends on the process ofosmosis, which is the movement of water mol-ecules (through a semi-permeable membrane)

from an area of higher concentration to anarea of lower concentration.

3. KEY QUESTIONS: How can we explain why thegoldfish and the sea star would die? The follow-ing explains how osmoregulation works (ordoesn’t work) in aquatic organisms:

■ Goldfish in salt water: The concentration ofwater molecules is greater inside the fishthan outside, because the salt outside takesthe place of water molecules. Since theosmotic pressure is greater inside the fishthan outside, water will leave the fishthrough its gill membranes by outwardosmosis. The goldfish, unable to compen-sate for the water loss, dies of dehydration(severe water loss).

■ Sea star in freshwater: The water moleculesmove from where they are more concen-trated (outside the sea star) to where theyare less concentrated (inside the sea star).The sea star is unable to eliminate theexcess water that enters due to inwardosmosis. The increased water pressure, orosmotic pressure, inside the sea star upsetscell function and causes death.

4. Aquatic animals such as the goldfish and seastar, which cannot adjust to environmentsthat vary greatly in salinity, are considered tobe poor osmoregulators. Salmon, on the otherhand, are considered to be extremely goodosmoregulators.

5. KEY QUESTION: Why is the salmon such a goodosmoregulator? The salmon is a migratory fishthat spends its juvenile stage in the riverwhere it is born (freshwater), and its adultstage in the ocean (saltwater). When thesalmon are in the ocean, the salinity of theirbody tissues is 18 parts per thousand (ppt),while the surrounding water is 35 ppt. Thereis a big difference in salinity between the fishand its environment, with the concentrationof water molecules greater inside the fish thanoutside. As a consequence, outward osmosisoccurs; water leaves the fish through its gillmembranes. To counter this water loss (and


avoid dehydration), the salmon drinks seawa-ter but excretes the excess salt from its gillsand in its urine.

6. When the salmon swims upstream to spawnin the river, it encounters zero salinity, whilethe salinity of its body tissues is still 18 ppt.Since the salinity is greater inside the fish thanoutside, the concentration of water moleculesis greater outside the fish (in the freshwater).This difference in the concentration of watermolecules causes water to enter the fish byinward osmosis. To counter this intake offreshwater, the salmon excretes the excesswater in the form of dilute urine.


Organize the class into groups of four to five stu-dents. Have them write an answer, in their ownwords, to the following question: Is the salmon agood osmoregulator or a poor osmoregulator? Explain.Call on students to write their answers on theboard. Read the responses aloud. Correct forspelling and grammar. Encourage discussion.

Homework Assignment

Read pages 457 (bottom)–460. Answer SectionReview questions 1–3 on page 460, and ChapterReview questions 12 and 17 on pages 464–465.

Chapter 19/Light and Sound in the Sea

INTRODUCTION

In Chapter 19, students will learn how two forms of energy—light and sound—affect the lives of marineorganisms. First, students will learn about the properties of light and how light behaves in water. Oceanic life-forms have evolved many structures and behaviors that relate to light in the water, such as vertical migration,camouflage, bioluminescence, and unusual color patterns. The basic properties of sound are explained, sincesound is an important form of energy underwater. Animals use sound to communicate in the ocean. Sonar isanother form of sound used underwater by animals and people.

■ Light is a form of solar energy; it penetrates best in clear, shallow waters. The area of light penetration in theocean is called the photic zone.

■ Phytoplankton, algae, and marine plants depend on light to carry out photosynthesis.

■ Some deep-sea animals produce their own light to help them see in the dark, attract mates, find prey, andcommunicate.

■ Sound is a form of energy produced by the vibration of air molecules. Sound travels faster in water than itdoes in air.

■ Marine animals use sound for communication, navigation, to deter enemies, and to stun prey. Sonar is animportant form of sound.


Aim: What is light and how does it behavein the ocean?



1. Define the electromagnetic spectrum.

2. Describe how light behaves in water.

3. Explain why the ocean looks blue.



Ask students to list some different sources of light(both natural and artificial). Explain how one ofthem is produced.


1. Different sources of light include the sunlight,incandescent light, fluorescent light, moon-light, “glo-stick” light, light from biolumines-cent organisms, and so on. The sun, of course,is the major source of light for Earth.

2. WRITE THE AIM: What is light and how does itbehave in the ocean? Light is a form of radiantenergy that comes to us from the sun. Visiblelight is the light that we can see and is one ofseveral forms of radiant energy, collectivelycalled the electromagnetic spectrum. (Refer stu-dents to Figure 19-1 on page 467.) Light thatreaches the ocean can be reflected or absorbed,and some of it is changed to heat energy inthe water.

3. KEY QUESTION: What happens to light when itreaches Earth? About 20 to 50 percent of thelight that reaches Earth either bounces off theatmosphere into space or is taken up by theatmosphere. Light that bounces off a surfaceis called reflected light. Light that is taken up bya substance is called absorbed light. Theremaining light (about 50 percent) passesthrough the atmosphere and reaches Earth’ssurface. Light that passes through a substanceis called transmitted light.

4. KEY QUESTION: What happens to light thatstrikes the ocean surface? When sunlight strikesthe ocean surface at an angle of 90 degrees (asat the equator), it penetrates the surface andcontinues in a straight line. When light entersthe water at an angle of less than 90 degrees, itdoes not continue in a straight path, butbends. This bending of light as it passesthrough substances of different densities, at anangle of less than 90 degrees, is called refrac-tion. (Refer students to Figure 19-2 on page468.)

5. KEY QUESTION: Why does the ocean look blue?Visible light is made up of a series of colors(i.e., different wavelengths), called the spec-trum. The color of any substance is actually the color of the wavelength of light that isreflected from that object back to theobserver’s eyes. When the ocean appears blue(or blue-green), it is because the blue wave-length has more energy than do the other col-ors and therefore can penetrate the watermore deeply. The blue color is scattered andreflected from deeper in the ocean (“deep bluesea”) back to the observer’s eyes. (Other colorsare absorbed.)


Project Figure 19-3 (on page 469) on the over-head. Ask students: Where should the person aimthe spear—directly at the fish, in front of the fish, orin back of the fish? Explain. To avoid missing dueto refraction, the person should aim in front ofthe fish.

Homework Assignment


LESSON 2 (109–110)

Aim: How do marine organisms use light tomake food?



1. Define the process of photosynthesis.

2. Explain how photosynthesis occurs.

3. Discuss the light and dark reactions.



Explain the following statement: All the energyin living things can be traced back to the sun.


1. Algae and plants capture sunlight to makefood. Animals feed on plants to satisfy theirenergy needs. Nearly all forms of life needlight, either directly or indirectly.

2. WRITE THE AIM: How do marine organisms uselight to make food? Project on the overhead ordraw on the board a marine alga or phyto-plankton, with labels showing the intake ofcarbon dioxide and water and the productionof the glucose and oxygen. The process bywhich algae and plants produce food and oxy-gen is photosynthesis.

2. KEY QUESTION: How can we describe the processof photosynthesis? Write the word equation forphotosynthesis on the board:

Six molecules of carbon dioxide plus twelve mole-cules of water, in the presence of light and chloro-phyll, yields one molecule of glucose plus sixmolecules of oxygen plus six molecules of water.

Now write the chemical equation for photo-synthesis on the board:

sunlight

6 CO2 + 12 H2O ⎯→ C6H12O6 + 6 O2 + 6 H2Ochlorophyll

3. KEY QUESTION: Where does the process of pho-tosynthesis occur in a plant? The process of pho-tosynthesis begins when light (radiant energy)is captured inside a plant cell by its chloro-plasts. The chloroplasts contain a green pig-ment called chlorophyll.

4. KEY QUESTION: How does the process of photo-synthesis occur? Photosynthesis can be dividedinto two phases: the light reaction, duringwhich oxygen is produced; followed by thedark reaction, during which glucose (sugar) ismade. When light enters chlorophyll, it ex-cites the electrons to a higher energy state,causing them to split water molecules. Theelectrons are transferred from one special mol-

ecule to another inside the chlorophyll in astepwise fashion known as the electron trans-port system. During electron transport, energyis released and converted into two energy-richchemical compounds: NADPH2 and ATP. Theproduction of ATP and oxygen occurs duringthe first phase (i.e., light reaction) of photo-synthesis.


Have students write out the word and formulaequations for photosynthesis. In a chorusresponse, have all the students read the formulaequation aloud.

Homework Assignment



Aim: What role does light play in the livesof marine animals?



1. Define bioluminescence.

2. Explain how bioluminescence occurs.

3. Discuss the role of light and color in fish.


Compare and contrast the following statements:Light makes life. Life makes light.


1. Light makes life during photosynthesis. Butlife can also make light.

WRITE THE AIM: What role does light play in thelives of marine organisms? In the ocean, some


living things can make their own light, in aprocess called bioluminescence. Noctiluca, adinoflagellate that glows in dark water, makeslight within its cell as a result of the followingchemical reaction:

Luciferin + Luciferase (enzyme) ⎯→ Light

(O2 + H2O + ATP at 25˚C)

2. The chemical compound luciferin reacts withthe enzyme luciferase in the presence of oxy-gen and water (at a temperature of about25 degrees Celsius) to produce light. Someshrimp, squid, and fish that inhabit the dimlylit waters of the mid-ocean region have patchesof bioluminescent tissue called photophores.The flashlight fish (genus Photoblepharun) pro-duces light by means of light-emitting bacteriathat live within a special organ located beloweach eye. (Refer students to Figure 19-5 onpage 473.)

3. KEY QUESTION: How is color used by marinelife? Marine organisms display all the colors ofthe spectrum. Color is due to the presence ofchemical compounds called pigments, foundin the cells called chromatophores. One type ofpigment, melanin, may have its granuleseither dispersed or contracted within the chro-matophores, making the cells look eitherdarker or lighter. The pattern of dark cells andlight cells helps an organism blend in with thecolor and texture of its natural background,providing camouflage. Some fish have counter-shading, a coloration that helps them matchtheir background in the sea. By contrast, somefish, like the rock beauty with its black andyellow coloration, has what is called color con-trast—a feature that makes a fish stand outagainst its background, which helps in speciesrecognition and as advertisement for the pur-pose of successful propagation.


Organize the class into groups of four to five stu-dents. Have some teams describe the role of lightand bioluminescence in the lives of various sea

creatures; have the other teams describe the roleof color in different marine animals. Read sum-maries aloud to the class.

Homework Assignment

Read pages 471–474. Answer Section Reviewquestions 1–3 on pages 474–475, and ChapterReview questions 12–13 on page 483 and 17–18on page 484.

LESSON 4

Aim: What role does sound play in theocean environment?



1. Describe the characteristics of a sound wave.

2. Explain how whales and dolphins echolocate.

3. Discuss the use of sonar by people.


Give students coiled (empty) seashells to hold upto their ears. Ask the students if they really hearthe sound of the sea inside the shells. Explain.


1. It may sound like the sea, but what you reallyhear inside the coil of a shell is the sound ofair molecules vibrating.

WRITE THE AIM: What role does sound play inthe ocean environment? Many ocean animals(e.g., fish, seals, and whales) use sound to helpthem survive.

2. Sound is a form of energy produced by objects(molecules) that vibrate, or move rapidly backand forth. Strike a tuning fork and touch thevibrating fork to the surface of a jar of water.


Notice the splash and the compression wavethat is transmitted (through the water) in alldirections. When a compression wave reachesa receptor (e.g., an ear), the quality of soundis perceived.

3. The parts of a sound wave in which the airmolecules are farther apart are called rarefac-tions. The parts of a sound wave in which theair molecules are closest together are calledcompressions. (Refer students to Figure 19-7 onpage 476.)

4. KEY QUESTION: How can we describe the char-acteristics of a sound wave? Sound can berecorded in the form of a sound wave on aninstrument called an oscilloscope. The highestpoint of a sound wave is the crest; the lowestpoint of a wave is the trough. The loudness, orvolume, of a sound is represented by theheight, or amplitude, of its wave. The pitch, orfrequency, of a sound wave is represented by itswavelength, which is the distance between twosuccessive crests. (Refer to Figure 19-8 on page476; project or draw this diagram on the boardas you describe its characteristics.)

5. KEY QUESTION: How do marine mammals usesound? In the depths of the ocean, where thereis little or no light, marine mammals (ceta-ceans) use sound to find their way and tolocate prey. The (underwater) use of sound fornavigation and for locating objects is calledecholocation. Cetaceans have no ears. Instead,cetaceans such as dolphins echolocate by send-ing out sound waves (clicks) through a moundof tissue in their forehead, called the melon,and receiving the returning sound waves,

called echoes, through the lower jaw, wheretheir nerve receptors for hearing are located.

6. The famous songs of the humpback whale havea deep (low) pitch because they are composedof low-frequency sound waves. In contrast, thesqueaking sound of the porpoise is recorded asa high-frequency sound wave. Cetaceans areknown to produce low-frequency sounds whenthey want to scan the environment, and emithigh-frequency sounds when they wish tofocus on a particular object.

7. People use an artificial form of echolocation,called sonar, to locate objects underwater andto learn more about ocean topography. How-ever, the use of low-frequency sonar by peoplecan have a harmful impact on cetaceans andother marine organisms.


Ask students the following question (to test theirunderstanding of sound): If a wave crashes on thebeach and there is no one around to hear it, is a soundproduced? Organize the class into several groupsto prepare their answer. Have the group leaderfrom each team read their answer aloud. Encour-age debate among the students.

Homework Assignment

Read pages 475–480. Answer Section Reviewquestions 1–3 on page 480, and Chapter Reviewquestions 9–11 on page 483 and 20–23 on page484.

Chapter 20/Tides, Waves, and Currents

INTRODUCTION

The great motions of the seas—tides, waves, and currents—are discussed in Chapter 20. Students will learnhow Earth’s movements in space affect the movements of the ocean’s waters. Tides are produced by the grav-itational pull of the moon and, to a lesser extent, the sun. Waves are produced by the force of the winds,


which results from Earth’s rotation. Students will learn about the properties of waves. The spin of the Earth isalso responsible for global ocean currents. Different types of currents are discussed in this chapter.

■ The tides are produced by the gravitational pull of the moon.

■ Winds produce waves; stronger winds cause larger, faster waves. However, tsunamis are caused by geologicactivity on the seafloor (not by winds or tides).

■ The Coriolis effect states that winds from Earth’s rotation cause the specific movements of surface waters(global ocean currents).

■ Other types of currents form as a result of differences in water density, seafloor topography, wave action,and shore interactions.


Aim: How can we explain the tides?



1. Define high tide and low tide.

2. Describe tidal change.

3. Explain and interpret a tide table.


Imagine that you go to the beach, drop yourtowel on the sand, and then go into the water fora swim. You come out a while later and find thatyour blanket is wet. Explain.


1. A towel that is left on a beach can get wetfrom the rising tide. The ocean waters arealways in motion. Currents circulate aroundthe world. Waves crash on the beach. Andwater is pushed and pulled by the tides.

2. WRITE THE AIM: How can we explain the tides?The periodic rise and fall of the surface of theocean is called the tide. The highest pointreached is called high tide, and the lowestpoint reached is called low tide. The verticaldistance between the high tide and low tide iscalled the intertidal range. (Refer to Figure 20-1on page 486.)

3. KEY QUESTION: Why is it important to know thetides? The tides affect various aspects of lifealong the shore. Storms hitting the coast athigh tide cause more damage (from flooding)than do storms hitting at low tide. Ships com-ing into port have to wait in deeper water forthe high tide before docking. The best time toschedule a field trip to observe living creaturesalong the shore is at low tide.

4. KEY QUESTION: How do you know when it ishigh tide or low tide? Local papers often printthe daily tide table for a region. An area thathas two high and two low tides each day has asemidiurnal tide. The East Coast (Atlantic) ofthe United States has a semidiurnal tidal pat-tern. The Gulf Coast has one high and onelow tide each day, called a diurnal tide. TheWest Coast (Pacific) has a pattern of mixed tides(similar to that of the East Coast), with twohigh and two low tides each day.


Hand out a map of a local coastal area (or well-known coastal area if you are landlocked). Havestudents work in groups to locate on the map thesites listed in that area’s tide table. Write in thehigh tides and low tides for each site. Comparestudents’ findings.

Homework Assignment

Read pages 485–488 (top). Answer Chapter Reviewquestions 1 on page 510 and 17 on page 512.



Aim: How can we explain the rhythm of thetides?



1. Explain how gravity causes tides.

2. Describe the tidal changes.

3. Discuss the role of the moon and the sun intidal change.


Project or write on the board the tide table shownon page 487 (Table 20-1). Why do tides change?Explain.


1. The tide table shows that the ocean advancesand retreats along the shore in a periodic fash-ion. Refer to the photographs in Figure 20-2,on page 487, which show the big differencebetween high tide and low tide at Mont-Saint-Michel near France.

2. WRITE THE AIM: How can we explain therhythm of the tides? A pulling force called grav-ity is responsible for the tides. Sir Isaac New-ton (1642–1727) discovered that gravity is apulling force exerted between any two bodiesin space. Earth and the moon exert a pullingforce on each other. The pull of the moon onEarth causes the ocean water that is facing themoon to be pulled toward the moon, produc-ing a tidal bulge, which is a high tide. (Refer toFigure 20-3, on page 488.)

3. KEY QUESTIONS: How does the tide vary duringthe month? When the sun and the moon arealigned with Earth, and pulling on it from thesame side, the highest tides, called springtides, are produced. Spring tides occur duringthe phases of the moon called new moon andfull moon, which are exactly two weeks apart.

When the pull of the sun and the moon onEarth are at right angles, a moderate neap tideis produced. (Refer students to Figures 20-4and 20-5, which show spring tides and neaptides, on page 489.) The highest tides occur atperigee, when the moon is closest to Earth; andthe lowest tides occur at apogee, when themoon is farthest from Earth. In addition, Earthmoves closest to the sun in January, called per-ihelion, and farthest away in July, called aphe-lion. The combination of perigee (close tomoon) and perihelion (close to sun) will pro-duce the highest tides of all.


Organize the class into groups of four to five stu-dents. Have each team sketch diagrams that showhow high tides and low tides are produced dur-ing the new and full moons. Ask the group lead-ers to draw them on the board. Students shouldcopy the correct diagrams into their notebooks.

Homework Assignment

Read pages 488–491. Answer Section Reviewquestions 1–3 on page 491, and Chapter Reviewquestions 6 on page 510 and 21–22 on page 512.


Aim: What is an ocean wave and how is itproduced?



1. Describe an ocean wave.

2. Explain how a wave is produced.

3. Calculate the height of a wave.


Imagine blowing on a bowl of hot soup. Describewhat happens to the soup’s surface.



1. When you blow on a bowl of soup, you seeripples in the liquid’s surface. A ripple is a smallwave. Waves are also produced in the ocean.

2. WRITE THE AIM: What is an ocean wave andhow is it produced? An ocean wave is an up-and-down movement of water on the oceansurface. The wind produces waves when itblows across the surface of the ocean. A gen-tle wind will produce a small wave or ripple; astrong wind will produce a larger wave.

3. KEY QUESTION: How does the wind produce awave? When the wind blows, it pushes on theocean surface, causing the water to lift. In gen-eral, the greater the speed and length of timeand distance that a wind blows, the greater thesize and speed of the waves it produces. (Pro-ject or draw on the board a copy of Figure20-8, page 492.)

4. KEY QUESTION: How can wave height be mea-sured? The height of a wave is the vertical dis-tance from the top, or crest, of the wave to thebottom, or trough, of the wave. Wave heightcan be measured using geometry. Refer to thediagram in Figure 20-9 on page 493. When thestern of a ship is in the trough, an observer onthe deck can line up the crow’s nest with thecrest of the wave. The reference points form aright triangle, in which BC is the height of thecrow’s nest, AC is the length from the stern tothe base of the mast, and AB (length fromstern, in trough, to crow’s nest) is thehypotenuse. The hypotenuse, which is theside of the right triangle opposite the rightangle (AB), would equal the height of thewave. You can use the Pythagorean theorem(a2 + b2 = c2), where BC is a, and AC is b, to cal-culate the height of side AB, or c, as shown onpage 493.


Organize the class into groups of four studentseach. Have the students calculate different waveheights. Substitute new values for sides BC andAC.

Homework Assignment

Read pages 491 (bottom)–493. Answer SectionReview question 1 on page 499, and ChapterReview questions 9–11 on page 511.


Aim: What are the characteristics of oceanwaves?


Student will be able to:

1. Calculate the speed of a wave.

2. Explain what causes a wave to break.

3. Discuss the different causes of waves.


Have students do “the wave” (a group activity) inclass. Describe how you would calculate the speedof the wave.


1. By doing “the wave,” the class is exhibitingcertain wave characteristics.

2. WRITE THE AIM: What are the characteristics ofocean waves? A group of people standing up insequence to do “the wave” illustrates a char-acteristic of waves called a wave train. A wavetrain is a series of waves, each followed byanother one moving in the same direction,which is caused by the blowing of a steadywind.

3. KEY QUESTION: How can we calculate the speedof a wave? The speed, or velocity, of any objectis found by dividing the distance traveled bythe time. When calculating wave velocity, youneed to know the distance (in meters) betweentwo successive waves, i.e., the wavelength, andthe time (in seconds) it takes for a wave topass a given point, i.e., the period. Thus, veloc-ity (V) = wavelength (W)/period (P).


4. Have students solve the following problem: Ifthe wavelength is 10 meters and the period is 5seconds, what is the speed of the wave? Call on astudent to work out the problem on the board.

V = W/P

V = 10 meters/5 seconds

V = 2 meters/second

5. Another characteristic of a wave is that it“breaks” on a beach.

KEY QUESTION: What causes a wave to break on the beach? Project or draw on the board acopy of Figure 20-11, on page 496. As a waveapproaches the shore, it enters shallow water,makes contact with the seafloor, and slowsdown due to friction. The wave breaks whenthe water depth below it is less than one-halfits wavelength.

6. KEY QUESTION: How can we explain wavesbreaking on the open seas? Strong winds pro-duce steep waves with narrow crests. The nar-row crests are easily blown off by the winds,creating a mixture of air and water known as awhitecap. Whitecaps are a sure sign of verywindy weather.

7. KEY QUESTION: In which direction do wavesmove? Create waves in a large tank or aquar-ium. Drop in a cork. Have students observethat the cork moves up and down, but doesnot horizontally. Ocean waves move up anddown. The energy of the wave moves out fromthe point of origin (recall the ripples), but thewater itself stays in place.

8. KEY QUESTION: What other conditions producewaves? The energy of an incoming tide cangenerate a high wave that travels several kilo-meters up the mouth of a river with a gentleslope and high tidal range. This advancingwave, called a tidal bore, may cause floodingupriver. A much more destructive wave is thetsunami, or tidal wave, caused by underseaearthquakes or volcanic activity. The origin, orepicenter, of a tsunami generates a great deal ofenergy, which reaches the ocean surfacethrough the water column and produces highvelocity waves. A tsunami slows as it

approaches shore, and its energy is convertedinto a lifting force that produces the giantwave.


Organize the class into several groups. Have eachgroup perform a wave train in class and then cal-culate its velocity.

Homework Assignment

Read pages 493 (bottom)–499. Answer SectionReview questions 2–3 on page 499, and ChapterReview questions 7 on page 510 and 15–16, 18,and 23 on pages 512–513.


Aim: What do we know about ocean cur-rents?



1. Identify global ocean currents.

2. Describe the location and direction of oceancurrents.

3. Explain how ocean currents move.


Display a world map. Point to the coast of Peru,in South America, and to the island of Tahiti, inthe Pacific Ocean. Ask how Thor Heyerdahl sailedon a raft from Peru to Tahiti. Explain.


1. In 1947, the Norwegian explorer Thor Heyer-dahl sailed on a raft from Peru to Tahiti, a dis-tance of 7000 km. He accomplished this by“hitching a ride” on an ocean current.

2. WRITE THE AIM: What do we know about oceancurrents? An ocean current is a mass of moving


Ocean Current Location Direction

Gulf Stream East Coast of U.S.A.–No. Hemisphere Clockwise

Canary Current West Coast of Africa–No. Hemisphere Clockwise

No. Equatorial Current North of Equator–No. Hemisphere Clockwise

West Wind Drift Mid-Atlantic & Pacific Ocean–No. Hemisphere Clockwise

No. Atlantic Drift North Atlantic Ocean–No. Hemisphere Clockwise

So. Equatorial Current South of Equator–So. Hemisphere Counter-clockwise

Brazil Current East Coast of So. America–So. Hemisphere Counter-clockwise

East Australia Current East Coast of Australia–So. Hemisphere Counter-clockwise

Benguela Current West Coast of Africa–So. Hemisphere Counter-clockwise

Peru Current West Coast of So. America–So. Hemisphere Counter-clockwise

seawater. The largest currents that move acrossthe ocean are called global ocean currents. Pro-vide handouts of Figure 20-15, which showsthe major ocean currents, or refer students tothe map on page 500.

3. KEY QUESTION: How can we describe the loca-tion and direction of the ocean currents? Organizethe class into several groups. Provide handoutsthat list the major ocean currents. Have stu-dents fill in the information on each current’slocation and direction.

4. KEY QUESTION: Why do some ocean currentsmove clockwise, while others move counter-clock-wise? The global ocean currents move in aclockwise direction in the northern hemi-sphere and in a counter-clockwise direction inthe southern hemisphere. The spinning ofEarth causes the winds to move in these direc-tions; and the winds drive the ocean’s surfacecurrents. This circular drift of the oceans inopposite directions in the two hemispheres isknown as the Coriolis effect. The continentsdeflect the ocean currents, causing them tomove in giant circles called gyres.


Have students identify the location and directionof five more ocean currents. Group leaders shouldfill in the information on the board and read italoud to the class.

Homework Assignment

Read pages 499 (bottom)–501. Answer SectionReview question 1 on page 507, and ChapterReview questions 12 and 19 on pages 511–512.


Aim: What conditions promote the developmentof ocean currents?



1. Identify the different types of ocean currents.

2. Explain how temperature and salinity differ-ences cause ocean currents.

3. Describe how and where upwellings occur.


When you tread water in the ocean (or in a lake),why is the water noticeably colder at your feetthan at your shoulders? Explain.


1. Surface water is warmer than the water below,because the sun heats the surface more.


2. WRITE THE AIM: What conditions promote thedevelopment of ocean currents? Temperature dif-ferences can produce vertical (subsurface)ocean currents. Just as air does, warm waterrises and cold water sinks, which promotes thedevelopment of ocean currents. Picture theocean as a giant pool heated by the sun. At theequator, the water is warmer, so it rises. At thepoles, the water is colder, so it sinks. As thewarmer water rises at the equator, the colderwater from the poles flows in to take its place,creating giant cycles of flowing water. Thismovement of water caused by a temperaturedifference is called a convection current, and itproduces a type of ocean current. Refer stu-dents to Figure 20-19 on page 503.

3. KEY QUESTION: How does a difference in salinityproduce ocean currents? Differences in salinitybetween two bodies of water can producesubsurface ocean currents. For example, theMediterranean Sea (3.9%) has a higher salin-ity than the Atlantic Ocean (3.5%), becausethe Mediterranean region is hot and dry, andits sea is enclosed, so more evaporation takesplace. When seawater evaporates, its salt is leftbehind, increasing its salinity. The saltierMediterranean water is denser, so it sinks andflows out toward the ocean; the less-saltyAtlantic is less dense, so its water flows inabove the Mediterranean’s to take its place.(See the NASA photo, Figure 20-17 on page503, which shows this flow of the Atlantic.)

4. KEY QUESTION: What do we know about deepocean currents? Fast-moving currents that movealong the continental slope are called turbiditycurrents. Turbid means cloudy, and the cloudi-ness is due to the presence of sediments in thecurrent as it rushes down the slope. Turbiditycurrents are responsible for carving V-shapedcanyons in the floor of continental slopes. Inaddition, there are slow-moving deep oceancurrents, called countercurrents, which flow in

a direction opposite to that of the ocean sur-face currents above them.

5. KEY QUESTION: How do ocean currents benefitocean life? Vertical ocean currents caused bydifferences in temperature and salinity canbring nutrient-rich waters from the seafloor upto the surface. The rising of such water fromthe deep is called an upwelling. Upwellings aresignificant because they transport phosphatesand nitrates (nutrients on which planktondepend) to the ocean surface. In turn, marinefish, birds, and mammals benefit from theabundance of plankton. As a result, upwellingsthat occur along a coast create excellent fish-ing grounds for people. (Refer to Figure 20-20on page 504.)

6. KEY QUESTION: How do waves and tides produceocean currents? After a wave breaks on thebeach, its forward momentum transportswater up the slope of the beach. The returningseaward current, or backwash, is called anundertow. A fast-moving current of water (froma breaking sandbar) that flows seaward fromthe beach is called a rip current. When the tideenters and leaves bays and inlets, the tidalchange produces swift-moving currents ofwater that run parallel to the shore, called tidalcurrents.


Organize the class into groups of four to five stu-dents. Have each team draw and describe a differ-ent type of ocean current. Ask the group leadersto read their descriptions to the class.

Homework Assignment

Read pages 502–507. Answer Section Reviewquestions 2–3 on page 507, and Chapter Reviewquestion 8 on page 510 and 13–14 and 20 onpages 511–512.

90

UNIT 7 MARINE ECOLOGY

Chapter 21/ Interdependence in the Sea

INTRODUCTION

The interactions of biotic and abiotic factors and the relationships among different kinds of marine organismsare discussed in Chapter 21. Students will see how the constant recycling of nutrients and resources is essen-tial to biological productivity in the ocean. Nutrient cycles are discussed, as are food chains, food webs, foodpyramids, symbiotic relationships in the sea, and ecological succession in marine environments.

■ The study of the interaction of living things with each other and with their ocean environment is calledmarine ecology. Biotic and abiotic factors interact within an ecosystem.

■ Nutrient cycles are crucial for the survival of organisms. Bacteria play an important role in the breakdownand recycling of nutrients.

■ Food chains are composed of producers, several (trophic) levels of consumers, and decomposers. Foodwebs are composed of many interconnected food chains, which include many predators and prey.

■ Food pyramids show the transfer of energy through food chains.

■ There are many examples of symbiotic relationships in the ocean. The three types of symbiotic relationshipsare mutualism, commensalism, and parasitism.

■ Ecological succession occurs in marine environments, such as coral reefs and rocky shores, with each com-munity of organisms slowly replacing the previous community.


Aim: What kinds of interdependence areseen in a marine environment?



1. Define interdependence.

2. Describe a food cycle.

3. Explain how an ecosystem works.


Give two examples of how you depend on othersand how others depend on you.


1. Life consists of relationships in which peopledepend on one another for their everydayneeds, such as food and shelter. In the marineworld, too, there are relationships among liv-ing things in which organisms depend on oneanother for survival. A relationship in whichorganisms interact to ensure survival is calledinterdependence.

2. WRITE THE AIM: What kinds of interdependenceare seen in a marine environment? Display, pro-ject, or draw on the board a diagram of a bal-anced marine aquarium tank. (Or refer to anaquarium that you may have set up in yourclassroom.)

UNIT 7 / MARINE ECOLOGY 91

3. KEY QUESTION: What marine organisms arefound in this aquarium? The living things in theaquarium may include algae, marine plants,snails, mussels, sea stars, fish, and bacteria.The living organisms in an environment arecalled biotic factors.

4. KEY QUESTION: What are some nonliving factorsin this environment? The nonliving factorsinclude temperature, pH, light, substrate, anddissolved gases. The nonliving factors in anenvironment are called abiotic factors. Theinteracting biotic and abiotic factors withinthe environment make up an ecosystem. Thisbalanced aquarium is its own ecosystem, andso is a tide pool or a coral reef. There are manydifferent ecosystems in the marine world. Thestudy of the interrelationships between livingthings and their environment is called ecology.The study of these relationships in the oceanis called marine ecology.

5. KEY QUESTION: Why is the aquarium consideredto be a “balanced” environment? In a balancedaquarium, nutrients (in foods) are recycled.The green algae and plants produce food viaphotosynthesis, so they are called producers.Animals such as the snail, sea star, fish, andmussels eat the algae and plants (food), sothey are called consumers. When producersand consumers die, their remains are brokendown and fed upon by bacteria, which arecalled decomposers. This movement of nutri-ents through the organisms in a balancedaquarium illustrates a food cycle.


Organize the class into groups of four studentseach. Have each team draw an aquarium thatillustrates interdependence through a food cycle.Ask the group leaders to draw the food cycles onthe board.

Homework Assignment

Read pages 515–518 (top). Answer Chapter Reviewquestions 5 on page 538 and 14 on page 539.


Aim: How does nutrient recycling occur in amarine ecosystem?



1. Identify the major nutrient cycles.

2. Explain how important elements are recycled.

3. Discuss the role of bacteria in the decayprocess.


Ask students to describe a recycling program thatthey participate in.


1. In certain neighborhoods, useful consumeritems such as glass, aluminum, plastic, andpaper are recovered and used again through aprocess called recycling.

2. WRITE THE AIM: How does nutrient recyclingoccur in a marine ecosystem? Organize the classinto five groups. Have each team read about,and draw in their notebooks, one of the fol-lowing nutrient cycles described in the text-book: carbon cycle (page 518), oxygen cycle(pages 518–519), nitrogen cycle (pages 519–520), sulfur cycle (pages 520–521), and phos-phorus cycle (pages 521–522). Have the groupleaders draw the cycles on the board while theother students copy them into their notebooks.

■ Carbon cycle: occurs as photosynthesizingplants and algae take in carbon, in the formof carbon dioxide (an inorganic compound),and produce carbohydrates (organic com-pounds); animals take in carbon compoundswhen they eat plants, then they give off thiscarbon, again in the form of carbon dioxide,as a waste product of cellular respiration; thecarbon once again becomes available toplants for photosynthesis.


■ Oxygen cycle: releases this crucial element asa by-product of photosynthesis from algaeand plants; oxygen is taken up by animalsand plants for cellular respiration; the car-bon and oxygen cycles together are calledthe carbon-dioxide–oxygen cycle, which showshow plants and animals are dependentupon one another.

■ Nitrogen cycle: makes available this ele-ment, through a natural decay process, forthe manufacture of proteins; nitrogenmoves from dead matter in the sea backinto marine plants through a series ofchemical reactions controlled by bacteria;one product of the nitrogen cycle is nitrate,which is produced through the action ofbacteria on ammonia (detoxified); nitratesare then absorbed by plants to synthesizeproteins.

■ Sulfur cycle: recycles this important elementfor protein molecules; sulfur moves fromdead matter in the sea back into marineplants through a series of chemical reac-tions controlled by bacteria; first, bacterialreaction breaks down wastes into hydro-gren sulfide (H2S); next, bacteria convertH2S into sulfur, not yet suitable for absorp-tion by plants; other bacteria convert thesulfur into sulfate (SO4), which is absorbedby algae to make proteins; animals gettheir sulfur when they eat plants and otheranimals.

■ Phosphorus cycle: supplies phosphorus to twoof the most important molecules in livingthings, ATP and DNA; living things needphosphorus for growth and energy; phos-phorus moves from dead matter in the seaback into marine plants through a series ofchemical reactions controlled by bacteria;this produces phosphate (PO4), which isabsorbed by algae and plants to make DNAand ATP; animals get their phosphoruswhen they eat plants, etc. The droppings, orguano, of many sea birds, is also rich inphosphorus and is harvested and sold com-mercially as fertilizer.


Have each group leader read aloud the descrip-tion of their team’s nutrient cycle.

Homework Assignment

Read pages 518–522. Answer Section Reviewquestions 1–3 on page 522, and Chapter Reviewquestions 13, 15, and 17 on pages 539–540.


Aim: What kinds of food relationships occurin a marine ecosystem?



1. Define food chain.

2. Describe food relationships in a food chain.

3. Construct a marine food chain.


Write on the board the following organisms:snail, algae, shark, crab, and octopus. Arrangethese animals in a correct sequence, going fromprey to predator.


1. The correct sequence (from prey to predator)for the “Do Now” is algae, snail, crab, octopus,and shark. Relationships between organismsthat are based on nutritional needs are calledfood relationships.

2. WRITE THE AIM: What kinds of food relation-ships occur in a marine ecosystem? A food rela-tionship where one organism serves as foodfor another organism is called a food chain. Theocean is made up of many food chains. Pro-ject on the overhead or draw on the board adiagram that shows the following food chain:


Phytoplankton → Zooplankton → Shrimp →Herring.

3. All food chains begin with a producer. Theproducer (phytoplankton) in the food chainconverts radiant energy into the chemicalenergy of glucose. The first consumer in thefood chain is called a primary consumer (thezooplankton). The animal that feeds on theprimary consumer is called a secondary con-sumer (the shrimp). A food chain may haveother consumers, such as a third-level or ter-tiary consumer (the herring), and so on. Eachfeeding level in a food chain is called a trophiclevel.

4. KEY QUESTION: How can we distinguish amongthe different consumers in a food chain? Con-sumers that only feed on plants or algae arecalled herbivores. Snails that graze on algae,and zooplankton that eat phytoplankton, areherbivores. Animals that consume only ani-mals are called carnivores. The meat-eatingshark is an example of a carnivore. A sea turtlethat consumes both plants and animals wouldbe called an omnivore. Humans also are omni-vores.


Organize the class into several groups. Have eachteam draw a marine food chain and identify thetrophic levels. Students can use the textbook as aguide. Ask the group leaders to draw their foodchain on the board and read its description to theclass.

Homework Assignment

Read pages 522 (bottom)–524. Answer SectionReview question 1 on page 527, and ChapterReview question 16 on page 540.


Aim: How do food relationships illustrateinterdependence?



1. Define food web and food pyramid.

2. Describe the relationships in a food web.

3. Explain energy dynamics in a food pyramid.


Project on an overhead the marine food webshown in Figure 21-7 on page 525, but first deletethe arrows. Ask students to use a pointer to showthe feeding relationships.


1. In this food relationship, several food chainsare interconnected with one another.

WRITE THE AIM: How do food relationshipsillustrate interdependence? When many foodchains are interconnected, they form a giantfood web. The consumers can be categorized aspredator and/or prey. Predators are the animalsthat kill and eat other animals. Prey are theanimals that are killed and eaten.

2. KEY QUESTION: Which animals in this food webare both predator and prey, and which ones areonly predator or only prey? All the animals areboth predator and prey, except for the cope-pods (herbivores that graze on diatoms) andthe orca (a top predator that is not preyed onby any other animal).

3. KEY QUESTION: What might happen to this foodweb if the larvae were suddenly wiped out byinsecticide spraying along the coast? It mightappear that killifish would decline in numbers,because they feed on the (mosquito) larvae.However, killifish also eat copepods (whichmight decline due to increased feeding onthem by killifish). In food webs, predatorsoften feed on more than one type of prey. Thisincreases their ability to survive when onefood source becomes scarce.

4. KEY QUESTION: How do the organisms in foodchains and food webs compare in terms of theirnumbers? Organisms in a food chain can be


arranged in a diagram called a food pyramid. Ina food pyramid of numbers, the population ateach higher trophic level is smaller than theone below it. The producers, e.g., plankton,would outnumber the primary consumers,e.g., snails. Likewise, there are more snailsthan there are lobsters that prey on them. Toppredators, e.g., sharks, are the least numerousof all. In other words, each prey populationoutnumbers the predator population above it.(Refer to Figure 21-8 on page 526.)

5. KEY QUESTION: What would happen if predatorsoutnumbered prey? Large populations of pro-ducers and prey are needed to sustain theconsumers at each higher trophic level. Other-wise, too many predators would die from alack of food.

6. KEY QUESTION: Which population of organismsin a food pyramid has the lowest amount of avail-able energy? Since animals cannot get theirchemical energy directly from the sun, theyneed to consume plants and/or other animals.However, at each trophic level, the animalslose a great deal of energy (about 90 percent)as heat in the process of carrying out their lifefunctions. Only about 10 percent of theenergy is stored in body tissues. Since there isenergy lost at each step in the food pyramid,the population of animals at the top of thefood chain, such as sharks, would have thelowest amount of available energy.


Organize the class into groups of four to five stu-dents. Have each group make up a food pyramid,using the textbook as a guide. Ask the group lead-ers to draw their pyramid on the board and readtheir description to the class.

Homework Assignment

Read pages 524–527. Answer Section Reviewquestions 2–3 on page 527, and Chapter Reviewquestions 7 and 9–11 on pages 538–539 and 18–21 on page 540.


Aim: What kinds of symbiotic relationshipshave marine organisms evolved?



1. Define symbiosis.

2. Explain why symbiosis evolved.

3. Compare mutualism, commensalism, andparasitism.


Draw on the board the following diagrams (ineach, have two fish facing each other): (a) twofish smiling; (b) one fish smiling, the other withno expression; and (c) one fish smiling, the otherfish frowning. Describe the relationships thatthese three drawings represent. (Remind studentsthat these are “cartoon fish”; real fish do notsmile or frown!)


1. In their struggle for existence, marine organ-isms have evolved a variety of different rela-tionships that aid their survival. Whenorganisms of different species live in closeassociation with each other, it is called sym-biosis, or a symbiotic relationship.

2. WRITE THE AIM: What kinds of symbiotic rela-tionships have marine organisms evolved? Thereare three main types of symbiotic relation-ships: mutualism, commensalism, and para-sitism. These are found in terrestrial andmarine species.

3. Examples of symbiotic relationships in marineorganisms include the following:

■ Mutualism: is a relationship in which bothspecies benefit; e.g., the clownfish livingamong the stinging tentacles of the seaanemone is involved in a mutually benefi-cial relationship. The clownfish benefits


because it is protected from predators by thesea anemone’s stinging tentacles (which donot harm the clownfish); the sea anemonebenefits by receiving scraps of food left overby the clownfish.

■ Commensalism: is a relationship in whichone species benefits, while the other is notaffected by the association; e.g., the remora(a bony fish) often swims below (or attachedto) the underside of a shark–the remorabenefits by eating leftovers from the shark’smeals; the shark appears to be neitherhelped nor harmed by the remora.

■ Parasitism: is a relationship in which onespecies (the parasite) benefits, while theother species (the host) is harmed; e.g., infin rot disease, bottom-dwelling fish such asthe flounder get infected by a disease-caus-ing microorganism. The fish is harmed (itsfins rot); the microbe lives by causing theinfection in host fish.


List on the board the following symbiotic rela-tionships: barnacles on the back of a whale; sealamprey and lake trout; cleaning wrasse andgrouper. Identify and match their types of sym-biosis with those of the cartoon fish from the “DoNow.” Have students go to the board to writetheir answers and explain them aloud to the class.

Homework Assignment



Aim: How do marine communities succeedone another over time?



1. Define ecological succession.

2. Describe succession on a bare island.

3. Explain why succession occurs.


Describe the changes that have taken place overtime on your street or in your town.


1. Neighbors and neighborhoods change overtime. Likewise, changes occur in the naturalworld. Marine communities can undergochanges over time.

2. WRITE THE AIM: How do marine communitiessucceed one another over time? The process bywhich one community of organisms graduallyreplaces, or succeeds, the previous communityof living things is called ecological succession.

3. Ecological, or biological, succession can occurundersea and on islands, as follows:

■ Succession underwater: If you place an objectsuch as a rock or glass bottle in a tide pooland examine it weeks later, you’ll see that athin coat of algae has begun to cover theobject, making it feel slimy. Over time, itwill be covered by small barnacles, then byseaweeds, and later still by mussels. Thesame process occurs on the hull of a ship.Organisms like barnacles that attach to asubstrate are called encrusting organisms.

■ Succession on an island: New volcanic islandsappear each year in the South Pacific, bornwhen the flow of molten lava from theseafloor reaches the ocean surface. After thelava cools into rock, conditions for lifebecome favorable. Winds and water bringspores and seeds. First, the lichens appear:plantlike organisms composed of an algaand fungus growing together. Acids in thelichen erode the rock, making it more suit-able for mosses to grow. The mosses erode


the rock into sediments, a condition suit-able for the germination of seeds. Grassessucceed the mosses and then eventuallygive way to shrubs and, finally, to commu-nities of trees. (Refer students to Figure21-11 on page 532 and Figure 21-12 on page534.)

4. KEY QUESTION: What causes one community to replace another community over time? Whenchemical and physical conditions in an areaare no longer suitable for the existing group oforganisms (such as after a natural disasteroccurs), a new community takes over. The firstcommunity to establish itself is called the pio-neer community. The pioneer organism inunderwater succession is the alga; on a vol-canic island, it is the lichen. The last stablecommunity to appear in any succession iscalled the climax community. On a volcanicisland, the climax community is composed of

trees. On an underwater substrate such as thehull of a ship, the climax community could bea bed of mussels. In other underwater regions,it could be a coral reef or a kelp forest.


Organize the class into groups of four studentseach. Have each group list, in correct sequence,the ecological succession of organisms in anunderwater area and on a volcanic island. Havegroup leaders explain why succession occurs inthese habitats.

Homework Assignment


Chapter 22/Pollution in the Ocean

INTRODUCTION

In Chapter 22, students will explore the impact of pollution in the marine environment. They will learn theimportance of clean waters to marine organisms and, ultimately, to people as well. The dumping of sewage,toxic chemicals, and solid wastes into the ocean has had adverse effects on various marine environments andmarine organisms, causing everything from algal blooms to fish kills, declines in seabird populations, and ill-nesses in marine mammals and humans. Actions being taken to prevent ocean pollution are also discussed.

■ Sewage treatment is essential for preventing the release of toxic microorganisms into the marine environ-ment.

■ Toxic chemicals from industrial and agricultural sources have had negative impacts on marine organismsthe world over. Solid wastes (litter) also injure marine life.

■ Toxic chemicals also reach humans by biomagnifying through the marine food chain.

■ Oil pollution, thermal pollution, and radioactive wastes all have an impact on the marine environment.

■ Clean, clear, well-oxygenated, non-acidic waters are essential for aquatic life-forms.

■ Government and private organizations have been working to reduce pollution and to protect the marineenvironment.



Aim: What is water pollution?



1. Define water pollution.

2. Explain why sewage treatment is necessary.

3. Calculate the coliform levels in water.


Why have some local beaches been closed toswimming in recent years? Explain.


1. Some local waterways of New York City havebeen closed to swimming in recent yearsbecause of water pollution, which poses ahealth threat to the public.

2. WRITE THE AIM: What is water pollution? Pol-lution describes a degraded condition in theenvironment that can cause harmful effectson living things, including humans. The sub-stances that degrade the environment arecalled pollutants. Water pollution occurs whenharmful substances enter the aquatic envi-ronment. One kind of water pollution iscaused by sewage. Sewage is composed ofhuman fecal wastes that are discharged intothe ocean and which may contaminate thewater with harmful, or pathogenic, bacteria.These pathogens can cause life-threateningdiseases such as typhoid fever, cholera, dysen-tery, and hepatitis.

3. KEY QUESTION: How is it determined that wateris contaminated with sewage? Water samples aretaken and tested for coliform bacteria, themicroorganisms that are found in the humancolon. The water samples are incubated for 24hours in petri dishes containing a nutrientmedia. After 24 hours, a single coliform bacte-rial cell will multiply into millions of cells that

form a raised mass of cells called a colony. Ifcoliform bacteria colonies are present, theyindicate contamination by sewage. The num-ber of colonies is counted and compared withthe Public Health Dept. Standards.

Health Standards re: Number Type of Water of Coliform Colonies

Drinking water Zero coliforms allowed

Swimming water Should not exceed 200 coliforms/

100 mL

Harbor water Should not exceed 2000 coliforms/

100 mL

4. Example: A 10-mL water sample was takenfrom a public beach and incubated for 24hours. After 24 hours, the petri dish containednine coliform bacterial colonies.

KEY QUESTIONS: What is the bacterial colonycount per 100 mL? Is the water safe enough toswim in?

5. Calculations: Count the number of colonies inthe petri dish that contains the 10-mL watersample and multiply by 10 to get the numberof colonies per 100 mL of water. Or calculateas follows: 9/10 mL = x/100 mL; 10x = 900; x =90 per 100 mL.

6. Result: If there are nine colonies in 10 mL,then there would be 90 colonies in 100 mL.

7. Conclusion: The water is safe enough for swim-ming in, because a count of 90 colonies doesnot exceed the 200-colony limit (standard) setby the Public Health Department.


Draw on the board several petri dishes, each witha different number of hypothetical bacterialcolonies (per 10-mL sample). Organize the classinto groups and have each team calculate thenumber of colonies per 100 mL of water for eachsample. Ask each group leader to state whethertheir water would be safe for drinking, swimming,or just boating?


Homework Assignment

Read pages 541–544. Answer Section Reviewquestions 1–2 on page 546, and Chapter Reviewquestions 9–11 on pages 565–566.


Aim: How good or bad is the water qualityin New York City waters?



1. Interpret a graph on water-quality trends.

2. Describe how a sewage-treatment plant works.

3. Discuss sewage treatment’s impact on NYCwaters.


Do you think New York City’s coastal waters aregetting better, staying the same, or getting worse?Explain.


1. There is a difference of opinion among thegeneral public concerning the quality of NewYork’s coastal waters. However, the overallquality seems to be improving.

2. WRITE THE AIM: How good or bad is the waterquality in New York City waters? Project on theoverhead, or draw on the board, a copy of Fig-ure 22-4 on page 546, which shows coliformtrends since 1970 in NYC waters. Have stu-dents copy the graph into their notebooks.

3. KEY QUESTION: What conclusions can be drawnfrom the graph about the overall quality of NewYork City waters? Overall, NYC coastal waterscontinued to improve in quality from 1970through the 1990s. Sudden increases in fecalcoliforms coincide with periods of heavy rain-fall. During heavy rains, the sewage-treatmentplants cannot handle the flood of water that

comes in from storm drains in the streets. Thisrunoff water, and the wastes that it contains, isdumped untreated into local waterways.

4. Contamination of water by sewage can bereduced or eliminated in a sewage-treatmentplant.

KEY QUESTION: How does a modern sewage-treatment plant work? Project on an overhead(or issue handouts of) a schematic diagram ofa sewage-treatment plant. A typical sewage-treatment plant contains large tanks thatdigest the fecal wastes. The solids settle to thebottom of the tanks, forming sludge, which isrecycled after further treatment and used as a fertilizer for crops. The liquid part of thesewage is treated with chlorine to kill patho-gens before it is discharged into waterways;this liquid discharge, or effluent, is greatlyreduced in pathogens compared to the rawsewage.


Have students write a brief description of thesewage-treatment process based on the diagramand/or the class discussion. Ask a volunteer toread their description to the class.

Homework Assignment

Read pages 544–546. Answer Section Reviewquestion 3 on page 546, and Chapter Reviewquestions 6 on page 565 and 22 on page 567.


Aim: How have toxic substances becomepart of the marine environment?



1. Define toxic chemicals.


2. Cite examples of toxic wastes.

3. Describe the health effects of toxic chemicals.


Write the following terms on the board: DDT,PCBs, mercury, crude oil, and radioactive wastes.What do all of these substances have in com-mon?


1. All of these substances are pollutants whenthey enter the marine environment. In her1962 book Silent Spring, marine biologistRachel Carson warned about the potentialdangers of chemical pollutants, or toxic sub-stances, to wildlife and the environment.

2. WRITE THE AIM: How have toxic substancesbecome part of the marine environment? Organizethe class into five groups, with each teamresearching a different pollutant. Informationon the pollutants can be found on the follow-ing pages: DDT (pages 547–548), PCBs (page548), mercury and other heavy metals (pages550–551), crude oil (pages 551–553), andradioactive wastes (pages 553–554).

■ DDT: is a toxic chemical used as an insecti-cide; was sprayed for more than 20 years onfarms, swamps, and coastal areas in the U.S.;has passed along food chains, from mos-quito larvae to marine birds, and causedthinning of eggshells; resulted in the declineof several marine birds; has been banned inthe U.S. since 1971, resulting in populationrecovery among threatened birds.

■ PCB’s: is a toxic chemical used in a varietyof consumer products; has been found tocause cancer in laboratory animals and issuspected of causing cancer and birthdefects in humans; has been discharged intowaterways from industrial plants from the1950s through the 1980s; has passed along

marine food chains, biomagnifying at eachtrophic level; toxic levels have been foundin the striped bass and the Canadian belugawhales; U.S. banned dumping of PCBs intoour waterways; resulted in a gradual declinein the PCB level in waterways such as theHudson River.

■ Mercury: is a toxic element used in industrialprocesses; first known to be a pollutant inMinamata Bay, Japan, in the 1950s andearly 1960s. Hundreds of people developedtremors, fell into comas, and died after eat-ing fish contaminated with mercury thatwas discharged from an industrial plant.Mercury can also enter the ocean from fac-tories in the form of smoke emissions,which are absorbed by moisture and fall astoxic rain. Mercury passes up the food chainand biomagnifies in large fish, such as tuna.The U.S. government sets a health limit ofno more than 0.5 ppm per fish. Other heavymetals that are dumped into the sea can betoxic when ingested in seafood.

■ Crude oil: is spilled into the sea as a result oftanker accidents and nonpoint source pol-lution (e.g., discharge of consumer prod-ucts); destroys marine life by suffocatingfish; coating marine birds and marine mam-mals with oil, and sinking to the seafloorand burying shellfish beds.

■ Radioactive wastes: have been dumped inlarge containers onto the seafloor; somehave begun to leak; have contaminated fishand invertebrates; rays can pass through liv-ing tissue, causing molecular damage;dumping in the ocean has been banned.


Ask each group leader to read the informationgathered about their toxic substance. Have stu-dents copy the important facts into their note-books. Encourage discussion. Note: You may wantto assign the topic of thermal pollution to a sixthgroup, if time permits.


Homework Assignment

Read pages 546–555. Answer Section Reviewquestions 1–3 on page 555, and Chapter Reviewquestions 7 on page 565 and 12–13, 15, and 17–19 on pages 566–567.


Aim: How can we get clean, clear waters inthe marine environment?



1. Define turbidity and hypoxia; describe howhypoxia occurs.

2. Explain water quality standards for dissolvedoxygen.

3. Discuss the role of an individual in cleaningup the environment.


Can an individual make a difference in cleaningup the environment? Explain.


1. Individuals can make a difference. For exam-ple, use paper bags instead of plastic bags. Par-ticipate in recycling projects. Organize an“Adopt-A-Beach” program in your communityand clean the beach on a regular basis. Form awater-watch team and monitor the quality ofa local body of water on a regular basis.

2. WRITE THE AIM: How can we get clean, clearwaters in the marine environment? Organize theclass into five groups. Have each team read intheir texts, and write in their notebooks, aboutone of the following water pollution-relatedtopics: turbidity (pages 556–557), dissolvedoxygen (pages 557–558), litter in the water(pages 559–560), solutions to pollution (pages

560–561), and groups against pollution (pages561–562).

3. Points that you may want to see mentioned bystudents could include the following:

■ Turbidity: is the level of clarity or murkinessof water; suspended particles cloud thewater, reducing light penetration and mak-ing it difficult for aquatic plants to carry outphotosynthesis; natural as well as unnaturalconditions can cloud waters; coastal watersmay turn cloudy from an algal bloom(caused by runoff containing fertilizers); tur-bidity can be measured using a Secchi disk.

■ Dissolved oxygen (DO): is the amount of oxy-gen dissolved in the water; DO levels inocean water range from about 1 to 12 ppm;the minimum DO level needed by fish andother aquatic animals to breathe is 4 ppm;below this level, a condition called hypoxia(low oxygen) occurs, leading to fish kills;hypoxia results from the activities of aero-bic bacteria associated with algal bloomsand/or the dumping of sludge; low DO lev-els cause the fish to suffocate.

■ Litter in the water: is solid waste or garbage,consisting of plastic, glass, or metal thatcannot be broken down by bacterial action;this is called nonbiodegradable litter; thou-sands of marine mammals, birds, reptiles,and fish die each year from getting entan-gled in plastic netting and other litter.

■ Solutions to pollution: include getting rid ofsolid wastes by recycling them, i.e., chang-ing them into useful products; incinerationof wastes; placement in landfills; and usingmore biodegradable products; e.g., someplastics manufacturers have introducedphotodegradable plastics to prevent injuriesto marine animals.

■ Groups against pollution: include the Interna-tional Maritime Organization, a U.N. groupthat regulates the disposal of chemicals,sewage, and trash by ships at sea; the EPAand NOAA, which are cosponsors of theCenter for Marine Conservation and its


Beach Cleanup Campaign; other govern-ment and non-profit environmental agen-cies that work to regulate and eliminate thedebris in the marine environment.


Ask each group leader to read the informationthey have gathered, and to write a brief summary

on the board. Have students copy the importantfacts into their notebooks. Encourage discussion.

Homework Assignment

Read pages 556–562. Answer Section Reviewquestions 1–3 on page 558 and 1–3 on page 562;and Chapter Review questions 14, 16, and 20 onpage 567.

Chapter 23/Conservation of Resources

INTRODUCTION

In Chapter 23—the last, but certainly not least, of all chapters—students will learn about the conservation, aswell as utilization and exploitation, of marine resources, both living and nonliving. The conservation of marinefisheries is discussed, in addition to the exploration for nonliving resources such as oil and minerals. Studentswill read about desalination techniques—important because most water on Earth is salt water. Different meth-ods of mariculture are described. Finally, the protection of rare and endangered marine animals is discussed.

■ Humans depend on many living and nonliving resources from the ocean. Some resources are renewable;other resources are nonrenewable.

■ The marine fisheries catch reached a peak by about the year 2000, but it is now declining due to overfish-ing. Most commercial fishing occurs in the neritic zone.

■ Oil from the seafloor is a valuable resource. High technology is used to locate and recover deposits of oilfrom seafloor sediments.

■ The ocean contains minerals that people mine and use, such as salt, manganese (in nodules), and othermetals.

■ Desalination of seawater is an important process for acquiring freshwater.

■ Mariculture is the farming of marine seaweeds, shellfish, and fishes.

■ Overhunting of marine animals has led to the extinction and endangerment of numerous species. Nowthere are special laws and marine sanctuaries to help protect endangered marine species.


Aim: What are the marine resources andhow can they be conserved?



1. Describe how fish are caught commercially.

2. Discuss measures to conserve fish resources.

3. Define maximum sustainable yield.



Make a list of natural resources that are found inthe ocean. Describe one in detail.


1. Items such as fish, oil, gas, minerals, and othermaterials that come from Earth are called nat-ural resources. The ways that people care for,protect, and manage these natural resourcesare called conservation.

2. WRITE THE AIM: What are the marine resourcesand how can they be conserved? One of our mostimportant resources from the ocean is fishbecause they provide food for the human pop-ulation. The commercial harvesting of fish isthe fisheries industry.

3. KEY QUESTION: How are fish caught commer-cially? Large numbers of fish are caught byships using hooks and long lines, and by huge“factory ships” using nets, such as trawling,purse seine, and gill nets. (Refer students toFigure 23-2 on page 573.) Japan, Russia, theUnited States, and China are the leading fish-ing nations.

4. KEY QUESTION: What effect has intensive fish-ing had on the fisheries? Project on an overhead(or refer students to) the graph in Figure 23-1on page 571. The widespread use of large netsby commercial fleets has increased the world’saverage fish catch between the years 1950 and2000. The largest number of fish that can betaken from a species’ population withoutthreatening its future population and harvestis called its maximum sustainable yield. Unfor-tunately, the stocks of popular food fish, suchas flounder, cod, and haddock, have beendeclining in recent years due to overfishing.

5. KEY QUESTION: What conservation measures arebeing used in marine fisheries? Fish populationsneed time to recover before they can increasetheir stock and be fished again. So, to reversethe decline in fish populations, the U.S. Con-gress passed the Magnuson Act, which forbidforeign fishing fleets from working within 333km of our coast. In addition, the federal gov-

ernment limited the catch size for several fish,such as salmon on the West Coast and sword-fish in the North Atlantic; and they tem-porarily closed the fishing grounds for cod,haddock, and flounder off Cape Cod, Mass.These measures have helped some fish popu-lations increase their numbers.


Have students work in groups to prepare a list ofmeasures that may help conserve and manageglobal fish stocks. Encourage discussion amonggroups.

Homework Assignment

Read pages 569–576 (top). Answer Section Reviewquestion 1 on page 581, and Chapter Reviewquestions 6, 9–11, 14–16, and 19 on pages 595–597.


Aim: How are we utilizing the naturalresources from the sea?



1. Define aquaculture and mariculture.

2. Describe how mariculture has increased foodresources.

3. Explain how other marine (non-food) resourcesare used.


Give students commercially packaged seaweed totaste. Have them describe the flavor.


1. Seaweeds are a good source of nutrients.Although relatively new as a food in the West,they have been eaten in the East for thousandsof years. Marine scientists are researching new


ways to use and wisely manage the ocean’snatural resources.

2. WRITE THE AIM: How are we utilizing the nat-ural resources from the sea? Organize the classinto five groups. Have each team research intheir textbooks, and copy into their note-books, information about the following re-sources that come from the sea: fossil fuels(pages 576–578), minerals (page 578–580),freshwater (pages 580–581), animal maricul-ture (pages 582–585), and plant mariculture(pages 585–586).

3. KEY QUESTION: How are we utilizing the ocean’snonliving resources? Have students come up tothe board to write brief summaries about theuse of fossil fuels, minerals, and water fromthe sea.

■ Fossil Fuels: include (in marine environ-ments) oil and gas, which come from theremains of long-dead organisms, mostlyplankton; hydrocarbons in the remains accu-mulate in layers on the seafloor and formthick deposits in the sedimentary rock; overtime, high temperatures and pressures fromEarth’s interior change the hydrocarbonsinto petroleum (either gas or oil).

■ Minerals: are solid, nonliving substancesconsisting of elements and compounds; themost common mineral extracted from theocean is salt; another valuable resource ismanganese nodules, which lie on the oceanfloor (see Figure 23-4, page 579); they arerich in manganese, iron, nickel, and cobalt;some nodules are too deep to mine.

■ Freshwater: can be produced from oceanwater by removing the salt, a process calleddesalination; one method, called a solar still,uses the sun’s energy to produce freshwater(students can examine Figure 23-5, page581); a new process called reverse osmosisis also used to produce freshwater fromseawater.

4. KEY QUESTION: How are we utilizing the ocean’sliving (animal and plant) resources? Overhar-vesting of fish, due to the demands of an ever-increasing human population, has stimulated

an interest in alternative ways of obtainingfood from the sea. One such method is to“farm” aquatic organisms, a process calledaquaculture. The process of farming organismsfrom the sea is called mariculture. Have stu-dents come up to the board to write brief sum-maries about the use of the following foodsources.

■ Animal mariculture: started in Japan with theraising of oysters along the shore; oystersproduce more than 100 million eggs at asingle spawning; the embryos, or veligers,attach to hard surfaces and develop intobaby oysters, which are cultivated in vastnumbers; techniques of oyster mariculturehave been adapted to raising mussels; crus-taceans are more difficult to farm becausethey are cannibalistic; the most widely cul-tured saltwater fish is the milk fish Chano,an important food item in Asia; the Japan-ese farm a popular ocean food fish, the redsea bream, in saltwater ponds. (Two types offish farming are shown in Figures 23-6 and23-7, on pages 584 and 585.)

■ Plant mariculture: farming of seaweeds is abig business; many popular consumer goodsare made from seaweeds; carrageenan, anextract from Irish moss (seaweed), is used tomanufacture toothpaste and ice cream;algin, an extract from kelp, is used as athickener and stabilizer in many processedfoods; the green alga Ulva is used by Hawai-ians in salads; the red alga Porphyra is usedto wrap boiled rice in sushi.


Have each group leader read aloud the informa-tion their group has placed on the board. Stu-dents should copy the information into theirnotebooks. Encourage discussion.

Homework Assignment

Read pages 576–586. Answer Section Reviewquestions 2–3 on page 581 and 1–3 on page 586,and Chapter Review questions 7, 12, 17–18, and22–23 on pages 595–598.



Aim: What do we know about the popula-tion sizes of marine species?



1. Cite examples of extinct and endangeredmarine species.

2. Distinguish between threatened and endan-gered species.

3. Explain how the manatee became an endan-gered species.


Project on an overhead the illustrations of thegreat auk (Figure 23-8, page 587) and of the man-atee (Figure 14-12, page 346). Ask which one isextinct. Explain.


1. The great auk is extinct. When a speciesbecomes extinct, it is completely gone fromEarth, never to be seen again. More than 500animal species (some of them marine) havebecome extinct in the Americas, just in thepast 500 years.

2. WRITE THE AIM: What do we know about thepopulation sizes of marine species? Some extinctmarine bird and mammal species are shown inTable 23-2 on page 587. By the mid-1800s, thegreat auk—a large, flightless seabird—wasalready extinct due to overhunting by hungrysailors.

3. KEY QUESTION: How are animals whose popula-tions are decreasing categorized? Animals that arethreatened with extinction are classified asendangered species. Animals that are at risk ofbecoming endangered are classified as threat-ened species. An example of an endangeredspecies is the manatee, the slow-movingmarine mammal that lives along the Florida

coast. Rapid development along Florida’s coastis responsible for the decline in the manateepopulation; and many are struck and killed bythe propellers of powerboats.

4. KEY QUESTION: What marine animals arethreatened and endangered? Project on an over-head, or write on the board, the threatenedand endangered marine animals listed in Table23-3, on page 589. Encourage students to dis-cuss the various reasons for the endangermentof these different species.


Organize the class into groups of four or five stu-dents. Have students consider the following ques-tions: Do humans have a responsibility to act asstewards in protecting wildlife? Are human popula-tions more important than populations of marine ani-mals? Have each team present its pros and cons.Encourage discussion and debate.

Homework Assignment

Read pages 586 (bottom)–588 (top). Answer Sec-tion Review question 1 on page 592, and Chap-ter Review questions 20–21 on pages 597–598.


Aim: What measures have been undertakento protect marine animals?



1. Describe conservation measures to protectendangered species.

2. Discuss the importance of habitat protectionin conservation.

3. Cite specific conservation laws that protectmarine species.



What is being done to protect endangered marineanimals, like the manatee?


1. Various measures have been undertaken toprotect marine species like the manatee.

WRITE THE AIM: What measures have beenundertaken to protect marine animals? The U.S.Congress has passed several acts to protectwildlife and their habitats, e.g., the WildlifePreservation Act, the Endangered Species Act,and the Marine Mammal Protection Act. TheEndangered Species Act prohibits the inter-state trafficking in endangered speciesobtained illegally in their country of origin.This act prohibits trade in items made, e.g.,from endangered whales, sea turtles, and soon.

2. KEY QUESTION: What is being done to protectthe habitats of endangered and threatened species?One way to protect endangered and threat-ened species is to eliminate or reduce humanintrusion into their habitats. The Florida Man-atee Sanctuary Act was established to stop the

decline in the manatee population. A marinesanctuary is a protected area in which no com-mercial activities are permitted, so that it pro-vides a safe habitat for marine organisms. Thefederal government has proposed and desig-nated numerous marine sanctuaries in U.S.waters as part of its National Marine Sanctu-ary Program. (Refer students to Figure 23-10on page 591.)


Organize the class into groups of four or five stu-dents. Have students consider the following ques-tion: Are you for or against economic developmentalong the coast in areas where there are threatened orendangered marine species? Have each team presentits pros and cons. Encourage discussion anddebate.

Homework Assignment


LESSON PLANS - i teach bio

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