protostomeschapter 33

poriferaeumetazoa

bilateria

cnidaria ctenophora

deuterostomiaprotostomia

lophotrochozoa

ecdysozoahemichordata echinodermata

chordata

gnathifera

gastrotricha

platyhelminthes nemerteagnathostomulida

rotifera acanthocephala

entoprocta

ectoprocta

mollusca

annelida

nematanematomorpha

tardigrada

arthropoda

onychophora

panarthropoda

acoela

root

rotifers• Phylum Rotifera—rotifers

• general characteristics• mastax• Marine or freshwater

filter-feeders• myxis

• Phylum Acanthocephala• proboscis with spiny hooks

• no digestive tract• protonephridia• dioecious• syncytial outer surface

• lacunar system distributes nutrients

flatworms• Phylum Platyhelminthes—

platy-flat, helmins-worm• Free-living or parasitic• Bilateral symmetry • Nervous system• Nutrition and Digestion

• Carnivorous or parasitic• Sac-like g-v cavity

Pharynx

Gastrovascularcavity

Mouth

Eyespots

Ganglia Ventral nerve cords

classification• Class Turbellaria

• Mostly free-living • Marine or freshwater• Predatory or detritivorous• Amazing regenerative powers

spine

distal cytoplasm

muscle

golgi

nucleus

tegument cell body

mitochondrion

parenchymal cell

flukes• Class Trematoda—flukes

• Vertebrate endoparasites• Adhesive sucker(s) or

hooks• Often with a multi-stage

life cycle

• Class Monogenea—• oncomiracidium (ciliated larva)• opisthaptor

prothaptor

mouth

sucker

opistaptoranchor

• Class Cestoda—tapeworms• scolex and proglottids • Monoecious• No gut

thus the area for absorption of nutriments. The bases ofspine-like and blade-like microtriches have an electron-dense ridge at their anterior edge. According toMacKinnon and Burt (1983) this ridge may function inpreventing the microtriches from bending forward andthus losing their grip against the mucosal epithelium ofthe host intestine.

The ultrastructure of microtriches can be used as ataxonomic character to be added to other characteristics(Richmond and Caira 1991; Hoberg et al. 1995; Cairaand Tracy 2002; Ivanov and Brooks 2002; Ivanov 2004;Gil de Pertierra 2004, 2005). In our opinion moreinformation of microtriches pattern could be useful forthe determination of species in proteocephalideans.

101

cytoplasm of tegumentmicrotrich

circular musclelongitudinal muscle

mitochondria

molluscs• Phylum Mollusca—

molluscs, mollusk• Marine, freshwater,

terrestrial trochophore

veliger

• Class Gastropoda• Univalve or having a lost or reduced valve• Classification—subclasses

• Prosobranchia• Opisthobranchia• Pulmonata

• Class Bivalvia—• No head or radula• bivalve -

• adductor muscles

• Class Cephalopoda—• Reduced or lost shell in most

• Chambered Nautilus (Nautilus)?• Cuttlefish • Octopus, squid

annelids• Phylum Annelida

• Prostomium, peristomium, trunk and pygidium • Excretory system consists of many nephridia • movement

Dorsal vessel

Setae

Intestine

NephrostomeFused nerve cords

Ventral vessel

Metanephridium

Septum

taxonomy• Class Polychaeta—

• Many burrowing, filter-feeding forms• euryhaline [opp. steno...]• Paired parapodia

three classes: Polychaeta, Oligochaeta, and Hirudinea (the latter two are in the clade Clitellata), clade Pogonophora

clitellata• Clade Clitellata• Class Oligochaeta

• paraphyletic • Epithelial gas exchange• Monoecious

• Clitellum• spermatheca

• Class Hirudinea• Predators or parasites• Parasitic - anesthetic,

anticoagulant saliva• No setae or parapodia

• Phylum Nemata—Nematodes or roundworms• general characteristics

• no cilia/flagella (except in one species)• longitudinal muscles only• eutely• Predatory, detritivorous, herbivorous, parasitic, etc...

• Phylum Tardigrada• Many similarities to

arthropods (molting, limbs, malpighian tubules)

• fluid feeders• Cryptobiosis --

(anhydrobiosis)

• Phylum Onychophora• velvet worms

arthropods• Phylum Arthropoda

• General characteristics• Metameric segmentation• Chitinous exoskeleton or

cuticle• modified limbs on each

metamere• open circulatory system

chelicerates• Subphylum Chelicerata

• Class Arachnida• Chelicerae• Two tagmata—prosoma

(cephalothorax) and opisthosoma (abdomen)

• Six pairs of limbs• no antennae• no mandibles

centipedes• Subphylum Myriapoda

• Class Chilopoda• Two tagmata: head and

trunk• tracheae with spiracles• Maxillipeds

• Class Diplopoda —• Two tagmata: head (with

ocelli) and trunk• tracheae• Detritivores or herbivores• some defensively toxic

Scolopendra heros, Texas up to 9 inches in length

crustacea• Subphylum Pancrustacea—

• General• aquatic, terrestrial, many are

planktonic• Monoecious or dioecious

(usually)• nauplius

• three appendages, medial eye

• Anatomy• Three tagmata: head, thorax, abdomen • Heavily calcified exoskeleton

• Ancestrally biramous appendages• Basal protopod

• lateral exopod • medial endopod

• gills for gas exchangeCephalothorax

Abdomencarapace

cheliped

antenna

antennule

walking legs

12 3 4

5

body wall protopod

epipod

exopod

endopod

• Class Malacostraca— • most of the large crustaceans

hexapods• Subphylum Hexapoda—

• very diverse• 3 tagmata• tracheae• malpighian tubules

• Success of hexapods:• versatile exoskeleton• segmentation -- efficient locomotion• tracheal systems• highly developed sense organs• complex behavior patterns• metamorphosis -- limited intraspecific competition

insects• Class Insecta —

• general characteristics• Three tagmata

• Three pairs of walking limbs on thorax

• Two pairs of wings on thorax • Development: egg --> larvae -->

pupa --> adult• Holometabolous• Hemimetabolous• Paurometabolous• Ametabolous