Chapter 31-1 By: Swetha Ramamurthy Katharine Wei Period 3!

A reptile is… 0 a vertebrate that has dry, scaly skin, lungs, and terrestrial eggs with several membranes. 0 These characteristics enable reptiles to live their entire lives out of water.

Evolution of Reptiles 0 Reptiles were the first to reproduce by not depositing eggs into water. 0 Mammal-like Reptiles – roamed the Earth by the end of the Pemian Period (about 245 million years ago). They displayed a mix of reptilian and mammal-like characteristics.

0 Dinosaurs – became dominant in Triassic Period. During the late Triassic and Jurassic period, a great adaptive radiation took place. This is why the Mesozoic Era is called “the Age of Reptiles”. Dinosaurs were everywhere, ranged in size, shape, and any other physical trait. They all belonged to either the Ornithischia “bird-hipped dinosaurs” or the Saurischia “lizard-hipped dinosaurs”. 0 Extinction – at the end of the Cretaceous Period, about 65 million years ago, a mass extinction occurred worldwide.

Functions 0 Can control their body temperature 0 Ectotherms: warm their bodies up using the sun, cool down using water or underground burrows 0 Wide variety of methods of feeding 0 Iguanas: herbivores, have long digestive systems to digest food 0 Snakes and others: carnivores, swallow food whole 0 Most reptiles eat insects, chameleons have a very long tongue to grab insects

Respiration 0 Reptiles have well-developed lungs because of spongy quality- provides more gas-exchange area; cannot respire through skin 0 Some have muscles on their ribs to expand and collapse the chest cavity while breathing 0 Some crocodiles have flaps of skin to separate the mouth from the nasal passage, so they can breathe through nostrils while the mouth is open

Circulation 0 Double-loop circulatory system -One loop: blood goes to and from lungs -Other loop: blood goes to and from rest of the body 0 Heart has 2 atria, most have 1 ventricle with a partial septum -Partial septum: wall separates rich and poor oxygen blood 0 Crocodiles and alligators have 2 atria and 2 ventricle

Excretion 0 Water-conserving excretory system, cloaca absorbs excess water 0 Urine flows from kidney to cloaca in some reptiles while in others it flows from storage in urinary bladder to cloaca 0 Water reptiles’ urine has ammonia, because the large amount of water can dilute the poison in it 0 Land reptiles convert the ammonia in their urine to less toxic uric acid

Response 0 Reptiles have a pair of sensory organs besides their nostrils that detect chemicals when reptiles flick their tongues 0 External eardrums and one bone takes sound to inner ear 0 Snakes can pick up vibrations in the ground through a bone in their skull, and even detect body heat of prey or predator 0 Movement: Large, strong limbs that make reptiles with legs move fast 0 Flexible, carries more body weight

Reproduction 0 Internal fertilization: sperm inside female body 0 Oviparous: develop outside mother’s body 0 Amniotic egg: develop without drying out 0 Shell and 4 membranes surrounding embryo -amnion: cushions embryo -yolk sac: provides nutrients for embryo -chorion: regulates transport of oxygen and carbon dioxide from surface of egg to embryo -allantois: stores waste

Groups of Reptiles 0 Lizards and Snakes: order: Squamata (scaly) 0 Lizards have legs, clawed toes, external ears, movable eyelids 0 Snakes are legless, large predators, vary greatly in size, some produce venom 0 Crocodilians: order: Crocodilia (alligators, crocodiles, caimans and gavials 0 Fierce carnivores, broad snout, protective of young,

0 Turtles and Tortoises: order: Testudines -Turtle: aquatic, Tortoises: terrestrial, Terrapin: salt water 0 Shell in skeleton, shell has carapace (dorsal), plastron (ventral) Backbone is center of carapace, pull into shells for protection 0 Large variety of habitats, not teeth only jaws, strong limbs 0 Tuataras: last of order: Sphedonta 0 Resemble lizards but no external ears, have scales 0 Has 3 rd eye on top of brain, senses level of sunlight 0 Reptiles are in danger from human activities (hunting), conservation efforts are needed