Class: Reptilia

{Amniotes

Who are they?• Reptiles• Birds• Mammals

Keratin is a proteinthat binds to a lipid(fat)to form a water repellentlayer that keeps water inside the animal fromreaching its skin.

A vertebrate that has a thin,tough, membranous sac that encloses the embryo or fetus.

It is almost a completely waterproof containerthat keeps the embryofrom drying outas it develops. • Yolk sac provides nutrients• Amnion protects and surrounds embryo.• Chorion – Allows gasexchange• Allantois – Holds wastematerials

The Amniotic egg

An important adaptation for vertebrates to reproduceon land.

See pp.788,789

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Groups of reptiles:

Order Squamata:(Snakes and lizards)

Order Crocodilians:(Alligators, crocodiles, caimans, gavials)

3. Order Testudines: Turtles and tortoises

4. Sphenodonta (Tuataras)

Only found on a few islands off the coast of New Zealand.

A reptile is a vertebrate that has dry, scaly skin,lungs and terrestrial eggs.• Characteristics enable reptile to live their entirelives out of water.

Body Temperature control:• Ectotherms – ‘Cold-blooded’ – rely

on their behavior to control their body temperature.

To warm up – bask in the sun in day or under water at night.To cool down – move to shade, go swim, go to underground burrows.

http://www.metacafe.com/watch/2602777/amazing_lizard_dance_dive_dune_bbc_wildlife/

Feeding:• Iguanas, tortoises – herbivores• Many others – carnivores• Chameleons have sticky tongues to catch

insects with.Respiration:• Use lungs – some snakes have one lung.• Crocodiles have flaps of skin that separate

their mouthfrom their nasal passages allowing it to breathe throughthe nostrils while their mouths are open and under water.

Circulation:• Heart with 3 or 4 chambers.

Excretion:•Urine produced in kidneys• Reptiles that live in the water – like crocodiles and alligators excrete most of their nitrogenous wastes as ammonia. (Drink a lot of water and water dilutes the ammonia in the urine)• Reptiles that live on land reduce urine to crystals of uric acid in the form of a pasty white solid. (Excess water is absorbed by the body and thus conserved).

Response:• Well developed brain.• Eyes can see color well.• Snakes have very good sense or smell.• Sensory organ in the roof of the mouth (Jacobson’s organ)can detect chemicals when the reptile flicks its tongue.• Simple ears – external eardrum• Snakes can detect vibrations in the ground from the bonesin their skulls.• Some snakes like the viper can detect the body heat of theirprey.

Movement: Walk, run, burrow, swim or climb.Aquatic turtles – developed flippers.

Reproduction:

• Internal fertilization.• Most oviparous – laying eggs that develop outside the mother’sbody.(Some lay eggs and abandon them (box turtles), others guard their nests until eggs hatch (alligators).• Some snakes and lizards are ovoviviparous – eggs hatch insidethe mother’s body and young are born alive.• Eggs have shells and membranes to protect the embryo fromdrying out.