REPTILE NOTES

QUICK QUESTION #1 What do you think makes a reptile, a reptile?

Reptile Basics  Definition: cold-blooded vertebrates with lungs, scaly skin, and a special type of egg (amniotic)  All these adaptations allow them to spend their entire life on land

The Amniotic Egg The Four Layers CChorion: lines the shell and regulates movement of gases in and out of the shell YYolk Sac: encloses the yolk (provides nutrients) AAmnion: encloses the fluid in which the embryo develops AAllantois: stores the embryo wastes until hatching

Tuataras (Rhynchocephalia)  Tuataras are the only surviving member of this clade.  Live on small islands off the coast of New Zealand  Active at night, hunt small animals  Gland on top of their head called “the third eye” because it contains light-sensing cells  Used to determine day length, not to see

Lizards and Snakes (Squamata)  Lizards have legs, clawed toes, external ears, and moveable eyelids  Snakes are legless lizards

Toxins  Hemotoxins: venom proteins that destroy red blood cells and disrupt blood clotting  Neurotoxins: venom proteins that disrupt nerve transmission

Alligators and Crocodiles (Crocodilia?  Alligators, crocodiles, and caimans  Live only in tropics and subtropics where weather stays warm

Turtles and Tortoises (Chelonia)  Turtles live in water, tortoises live on land (generally)  2 parts of a turtle shell: carapace (dorsal) and plastron (ventral)  Back is fused to the carapace  Tortoises can have more dome-shaped shells  If aquatic, legs have developed into flippers

How do they eat?  Many reptiles, many forms of feeding from herbivorous to carnivorous

Digestion and Excretion  Short, simple, and slow digestive system  Herbivours eat rocks to help break down food  “Urine” stored in cloaca  The cloaca can remove large amounts of water from “urine” and restore it to the body or use glands to excrete salt  Many reptiles excrete a nitrogen based waste in the form of uric acid rather than urine

Respiration  Reptiles have lungs and inhale and exhale using various mechanisms.  Some have flaps of skin that can separate the mouth from the nasal passages…so they can breathe through their nose while their mouth is open  And some…have a special tube at the bottom of their mouth that can be extended outward so they can breathe while swallowing

Internal Transport  Can be argued that they have a three or four chamber heart (both are correct)  Crocodiles have a four chambered heart. All others have a partially divided ventricle

How do they survive? response  Senses are well developed  Great sense of smell…nostrils near the mouth and Jacobsen’s organ  Snakes can’t hear (no eardrum)….others have only a simple ear  Complex eyes  Heat sensing capabilities…  Some can detect warmth given off of bodies of the small animals they eat Ectothermic : body temperature is determined by the environment Endothermic : body temperature holds at a constant level

How do they survive? Movement  Reptiles with legs have larger, stronger limbs than amphibians  Reptiles without legs move by pressing large, ventral scales against the ground by expanding and contracting muscles around their ribs

QUICK QUESTION #2 Explain how animals like snakes can move without legs

How do they Reproduce?  Most reptiles are oviparous with internal fertilization  Some lizards are ovoviviparious ~ they hold the eggs in their bodies until they hatch and then give birth to live babies