Reptiles

Julian Martinez

What is a reptile?• A reptile is a

vertebrate that has dry, scaly skin, lungs, and terrestrial eggs with several membranes.

• These allow the reptile to live it’s whole life out of water.

Evolution

• Evolved from amphibian-like ancestors• After the Carboniferous Period, lakes

and swamps dried up, which reduced some available habitat for water-dependent amphibians.

Mammal-like Reptiles

• Mixture of reptilian and mammalian characteristics

• Eventually came to dominate many land habitats

• During the Triassic Period (215 million years ago) Dinosaurs dominated.

Enter the Dinosaurs

• Ranged in sizes from small to enormous!

• Some ran on two legs or lumbered on four.

• All dinosaurs belonged to 1 of 2 groups– Ornithischia (Bird-Hipped)– Saurischia (Lizard-Hipped)

Exit the Dinosaurs

• At the end of the Crustaceous Period (65 mill. Years ago) mass extinction occurred.

• Multiple natural disasters– Volcanic eruptions and lava flows,

the dropping of sea level, and a huge asteroid or comet hitting what is now the Yucatán Peninsula in Mexico.

– Caused huge forest fires and dust storms ridding of the dinosaurs

Form and Function

• Well-developed lungs; a double-loop circulatory system; strong limbs; internal fertilization; and shelled, terrestrial eggs are the other adoptions that have contributed to the success of reptiles on land.

Body Temperature Control

• Reptiles control their body temperature by moving locations.

• To warm up, they bask in the sun during the day or stay underwater at night

• To stay cool, they move to the shade or go swimming, or take shelter in underground burrows.

• Ectotherms: An animal that relies on interactions with the environment to help it control body temp.– Turtles and snakes

Feeding

• Wide range of foods• Most animals eat insects.• Carnivores– Snakes- small animals and

bird eggs– Crocs/Alligators- fish and

land animals• Herbivores– Iguanas- tears plants and

swallows the chunks

Respiration

• Many reptiles have muscles around their ribs that expand the chest cavity to force air out.

• Snakes only have 1 lung.• Spongy lungs– Providing more gas

exchange area than amphibians

Circulation

• The alligator and crocodile have the most developed hearts– 2 atria and 2 ventricles

• Reptile hearts have 2 atria and 1 or 2 ventricles

• Double loop circulatory system– One brings blood to and

from the lungs– Brings blood to and from

the rest of the body

Excretion

• Urine produced in the kidneys• Reptiles’ urine contains ammonia or uric acid• Crocs and alligators consume a lot of water,

which dilutes the ammonia in the urine and carries it away.

• Land animals convert the ammonia into uric acid.– Less toxic than ammonia

Response

• A reptile’s brain is smaller than that of an amphibian.

• Day active animals have better vision than others.

• Snakes have a great sense of smell because of their lack of eyesight.

• Reptiles have 2 sensory organs at the top of their mouths the detect chemicals when reptiles flick their tongues.

Movement

• Reptiles with legs have stronger, larger limbs that enable them to walk, run, swim, burrow, or climb.

Reproduction

• Internal fertilization• Reptiles lay eggs.• Most reptiles have penis-like

organs that deliver sperm to the female’s cloaca.

• Some snakes and lizards are ovoviviparous

Groups of Reptiles

• The four surviving groups of reptiles are snakes and lizards, crocodilians, turtles and tortoises, and the tuatara.

Lizards and Snakes

• Modern lizards and snakes belong to the order squamata, which means “scaly reptiles”

• Lizards– Legs– Clawed toes– External ears– Movable eyelids

Crocodilians

• Fierce carnivores that feed on other animals.

• Very protective over their young

• The females guard the eggs and carries them to a nursery area and watches over them.

• Only found in tropics, or subtropics where climate remains warm all year

Turtles and Tortoises

• Belong the order Testudines

• Have shells built in their skeletons

• Shell consists of 2 parts– Carapace- the part of the

exoskeleton that covers the cephalothorax.

– Plastron- Ventral part of the shell

Tuataras

• Surviving member of the order Sphenodonta• Found only on a few islands off the coast of

New Zealand• Lack external ears and retain primitive scales

Ecology

• Endangered species • Habitat being destroyed• Humans hunt reptiles

for food, to sell as pets, and for their skin.

• Sea turtle recovery programs– Help babies get a head

start on survival