Class : Reptilia

General Characters1-Reptiles represent the first class of vertebrates fully

adapted for life in dry places on land.

2- The study of reptiles is called Herpetology (Gr.,

herpeton, reptiles).

3- Predominantly terrestrial, creeping or burrowing,

mostly carnivorous, air-breathing, cold-blooded,

mostly oviparous and tetrapodal vertebrates.

4-Skin dry and devoid of glands.

5- Body bilaterally symmetrical.

6- Endoskeleton bony. Skull with one occipital condyle.

7- Exoskeleton of horny epidermal scales, shields, plates

and scutes.

8- The body consists of head, Neck, trunk and tail .

9- Mouth terminal. Jaws bear simple teeth.

10- Limbs 2 pairs, pentadactyle. Digits provided with

horny claws. However, limbs absent in a few lizards

and all snakes.

11- Heart usually 3-chambered, but 4-chambered in

crocodiles.

12- Respiration by lungs throughout life.

13-Lateral line system absent.

14- Sexes separate. Male usually with muscular

copulatory organ.

15- Fertilization internal. No metamorphosis. Young

resemble adults.

Subclass I. Anapsida

Subclass II. Eurvapsida (extinct)

Subclass III. Parapsida (extinct)

Subclass IV. Synapsida (extinct)

Subclass V. Diapsida

Class Reptilia usually divided into 5 subclasses;

three of them are extinct.

Order : Chelonia

Order : Squamata

Order : Crocodilia

Order : Chelonia

1- Body short, broad and oval.

2- Limbs clawed – in aquatic types are webbed, paddle-like.

3- Body encased in a firm shell of dorsal carapace and ventral

plastron.

4-Thoracic vertebrae and ribs usually fused to carapace.

5-Teeth absent. Skull is Anapsida

Order :Squamata*(Squama = scale)

1- Advanced, small to medium, elongated reptilians.

2- Limbs clawed, absent in snakes and some lizards.

3- Exoskeleton of horny epidermal scales, shields and

spines.

4- Skull diapsida.

5- Male with eversible double copulatory organs.

** Squamata divided into 2 distinct suborders;

Lacertilia and Ophidia

Order : Crocodilia

1. Large-sized, carnivorous and aquatic reptiles.

2. Tail long, strong and laterally compressed.

3. Limbs are short but powerful, clawed and

webbed.

4. Skin thick with scales, bony plates and scutes.

5. Skull diapsida. Teeth numerous and strong

Some Examples of Class

Reptilia

1- Chelonia

2- Hemidactylus

3- Chamaeleon

4- Naja

5- Crocodylus

Class : Reptilia

Subclass : Anapsida

Order : Chelonia

Family : Cheloniidae

Genus : Chelonia

1- They are ancient reptiles that have remained

relatively unchanged for 175 million years.

2- They show the greatest departure from the typical

reptilian plan. However, they are easily identified by

their armored shell of bony plates.

3- Teeth are absent in all turtles being replaced by a

horny beak-like structure.

4-Their limbs are heavy as required for carrying the

unusually heavy body.

5- Aquatic forms (comparing to terrestrial forms)

have reduced shells and limbs modified as

flippers or paddles for swimming.

6- When the animal is threatened with danger, the

head, neck, limbs and tail are withdrawn into the

shell.

7- Although they breathe by lungs, they may remain

under water for a considerable time.

8- All turtles hibernate during colder days.

9- The leatherback turtle, Dermochelys coriacea, is

the largest turtle. It may reach a length of 2.5

meters and attain a weight of 600kg.

10- Carnivorous and attain age of 200 to 400 years.

Class : Reptilia

Subclass : Diapsida

Order : Squamata

Suborder : Lacertilia

Family : Gekkonidae

Genus : Hemidactylus

Hemidactylus

1-Common house or wall lizards are known, as geckos.

2- These are small lizards, about 30 cm in length having tails shorter than head and trunk.

3- Tongue is sticky and protrusible.

4- The underneath of fingers and toes have adhesive lamellae which aid in climbing vertical surfaces or walking across ceilings.

5- Unlike most lizards some geckos are vocal, making clicking sounds.

Class : Reptilia

Subclass : Diapsida

Order : Squamata

Suborder : Lacertilia

Family : Chamaeleonidae

Genus : Chamaeleon

Chameleon

1- Body is compressed, skin granulated and head with a prominent hood.

2- Feet with digits arranged in groups of 2 and 3 to grasp branches firmly. Additional security is provided by a prehensile tail.

3- The very large tongue can be projected forward with great speed to capture insects, which stick to its sticky tip.

4- The eyes are elevated and move independently.

5- Chameleons are famous to change their body colours rapidly to blend with their surroundings.

Class : Reptilia

Subclass : Diapsida

Order : Squamata

Suborder : Ophidia

Family : Elapidae

Genus : Naja

1- It known as (The Egyptian cobra) Poisonous snakes.

2- The body is cylindrical and stout with a long tail.

Length is about 1-2 metres.

3- The head is depressed and slightly distinct

from the neck.

4- Neck can dilatate supported by ribs.

5- This species prefers to eat toads, but it will prey on

small mammals, birds, eggs, lizards and other snakes.

Naja haje

Class : Reptilia

Subclass : Diapsida

Order : Crocodilia

Family : Crocodylidae

Genus : Crocodylus

Crocodilians

1- Include some of the largest living reptiles.

2- These are formidable carnivorous lizard-like

creatures.

3- live mainly in tropical freshwater rivers.

4- Their body is long, depressed.

5- The head elongated into a flat snout.

6- Massive tail is laterally compressed, forming

a powerful appendage.

7- Limbs are short but strong, pentadactyle, clawed and

webbed.

8- Skin is thick, with horny scutes.

9- It grows to 8-9 meters.

10- These large reptiles are well adapted for an aquatic

existence. Nostrils, eyes and ear openings are placed

high on the head and remain exposed even when the

whole animal is immersed in water. Thus, breathing,

seeing and hearing remain uninterrupted.