Reptiles Section 31-1

Section 31-1 Learning Targets Describe the characteristics of reptiles Explain how reptiles are adapted to life on land Identify the four living orders of reptiles

Classification Kingdom: Animalia –Phylum: Chordata Subphylum: Vertebrata –Class Reptilia

What is a Reptile? Vertebrate Dry, scaly skin Breathe with lungs Terrestrial eggs Internal fertilization

Form & Function BODY TEMP CONTROL –ECTOTHERMS: rely on external environment to control temp Lay in sun to warm up, move in shade to cool down Feeding –Reptiles can be herbivores or carnivores –Most are carnivores that eat insects

Form & Function RESPIRATION: –LUNGS: spongy, so more gas exchange than amphibians NO gas exchange thru skin –Muscles expand rib cage to inhale –Collapse the cavity to exhale

Form & Function CIRCULATION: –Efficient Double-Loop One loop brings blood to and from the lungs Other loop brings blood to and from the rest of the body –2 atria; 1 ventricle (partially divided) –Alligators have 4-chambered heart

EXCRETION: –Kidneys produce urine Nitrogenous wastes are excreted in the form of ammonia or uric acid Aquatic reptiles usually excrete ammonia that has been diluted with water –Terrestrial reptiles usually excrete uric acid as crystals (conserves H 2 0)

Form & Function RESPONSE: –Active during day; complex eyes; see color well –Detect smell and chemicals on roof of mouth EX: snake flick tongue to bring chemicals into mouth Some snakes can even detect the body heat of their prey! REPRODUCTION –All reptiles reproduce by INTERNAL FERTILIZATION Male deposits sperm inside body of female –OVIPAROUS (most) Lay eggs that develop outside of body –Ovoviviparous (some snakes and lizards)

Reproduction, cont’d. Unlike amphibian eggs, which need to develop in water, the shell and membranes protect the reptilian embryo from drying out –Reptiles use an AMNIOTIC EGG (hard shell) Four membranes surround the embryo inside the shell: –CHORION –YOLK SAC: serves as food supply –AMNION: fluid-filed sac surrounds / cushions embryo –ALANTOIS

Groups of Reptiles

4 Orders of Reptiles Order Squamata ( Lizards and Snakes) Order Crocodilia (alligators and crocodiles) Order Testudines (Turtles and Tortoises) Order Sphenodonta (Tuatara)

Order Squamata Snakes and Lizards –Evidence suggests that snakes evolved from lizards that burrowed –Snakes retain small leg bones even though they have no legs Types of Lizards –Komodo Dragon –Gecko –Chameleon –Bearded Dragon Types of Snakes –Cobra –Rattlesnake –Copperhead

Frilled Lizard

Gila Monster

Horned Lizard

Cobras and Coral Snakes Cobras and Coral snakes –Inject a neurotoxin that causes paralysis and breathing difficulties Coral SnakeCobra

Sea Snakes Spend most of their life underwater Tails are shaped like a paddle to help them swim

Adders and Vipers Adders and vipers –Very venomous

Rattlesnakes Rattlesnakes and water moccasins (cottonmouths) –Inject a hemotoxin which causes destruction of the blood and tissue –The area of the bite becomes swollen and dark.

Copperheads

Order Crocodilia Crocodiles, Alligators, Caimans and Gavials Only reptile group that takes care of their young (very protective of young) Adapted to stealth hunting - eyes and nostrils are above the head, so the body can remain submerged –They attack when animals (or humans) come to the water shore to drink

Crocodiles –Pointier snout and teeth stick out –Live in fresh or salt water in Africa, India and Southeast Asia Alligators –Snout that is more rounded and teeth fit into a socket –Live only in fresh water and are almost exclusively in North and South America

Crocodiles Alligators

Order Testudines Turtles and Tortoises –Characterized by a shell that is fused to the turtle's spine It cannot be removed, nor can a turtle crawl out of it. –The top of the shell is the carapace, the bottom of the shell is the plastron. Turtles - generally live in waterTurtles –Sea turtles migrate long distances to lay their eggs at the same beach they were born at. Tortoises - live on land and have rounded bodiesTortoises

Order Sphenodonta Tuatara only surviving member Known as a "living fossil" –They have survived unchanged for 150 million years Has a “third eye” above brain can sense the level of sunlight (function unknown) Only lives in New Zealand and is in danger of becoming extinct Tuataras have distinctive head spikes

That’s All folks!

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