31-1 Reptiles

1. 31-1 Reptiles Essential Question What is a reptile?

2. What is a reptile? • Share three characteristics: • Scaly skin • Eggs with protective membranes • Lungs • Also: • three-chambered heart • Cloaca • Ectotherms (cold-blooded – body temperature regulated by environment) • Disadvantage of scaly skin – must shed it when they grow.

3. Evolution of Reptiles • Fossil of first reptile dates back to Carboniferous Period some 350 million years ago. • Dinosaurs became dominant species 215 million years ago during Triassic period • Two separate groups of reptiles swam in seas – became ancestors to modern turtles, crocodiles, lizards, and snakes. • Ranged in seize from small to enormous • Modern birds evolved from dinosaurs that had developed feathers • Died out 65 million years ago

5. Body Temperature Control • Reptiles are ectotherms and can not control their body temperature • Body temperature is a result of climate • To warm up they go in sun • To cool down they go into water, or under rock or leaves • Can not live in cold weather climates

6. Body Temperature Control • Reptiles are ectotherms (cold-blooded) and cannot control their body temperature • Body temperature result of climate • To warm up they go into sun • to cool down, they go into shade or into burrows or go for swim • Can not live in cold weather climates

7. Feeding • Eat a wide variety of food • Long digestive tract allow some to eat plants • Most are carnivorous eating fish (crocodiles) • Most reptiles eat insects (chameleons)

8. Respiration • spongy lungs with muscles around lungs that allow them to expand the chest cavity • Most reptiles have two lungs • Cannot exchange gases through skin • Some species of crocodiles have flaps of skin that allow them to breathe with nostrils while mouth remains open

9. Circulation • Double-loop circulatory system • One loop brings blood to and from lungs and other loop brings blood to and from rest of body • Lizards and snakes have a three-chambered heart (like amphibians) with two atria and one ventricle with a partial septum (wall that separates chambers) • Crocodiles and alligators have four-chambered heart (similar to birds and mammals)

10. Excretion • Urine produced in kidneys and contains either ammonia or uric acid • Water animals like crocodiles drink large amounts of water • Land animals like snakes do not urinate but instead reabsorb and change it to uric acid which is then eliminated as a white pasty solid

11. Response • Brain similar to amphibian but with larger cerebrum and cerebellum • Those active during the day have well developed eyes that can see color • Many snakes have well developed sense of smell • Simple ears with external eardrum and a single bone that conducts sound to inner ear • Some like viper can detect body heat of prey

12. Movement • Reptiles with legs have strong limbs that allow them to walk, run, burrow, swim, or climb. • Legs of aquatic reptiles have evolved into flippers • Backbones help them to move

13. Reproduction • All use internal fertilization • Males have penis-like organ and deliver sperm into female cloaca • After fertilization, embryos are covered with membranes and a leathery shell • Most are oviparous – laying eggs that develop outside of mothers body • Some snakes and lizards are ovoviviparous carrying eggs in her body giving birth to live young.

14. Reptiles have two reproductive strategies. • Oviparous reptiles deposit eggs into an external nest. • Viviparous reptiles retain eggs and give birth to live offspring.

15. Amniotic egg

16. Groups of Reptiles • since dinosaurs disappeared, modern reptiles have evolved into four groups: • Lizards and snakes (order Squamata) • Crocodiles (order Crocodilia) • Turtles and Tortoises (order Testudines) • Tuataras (order Sphenodonta)

17. Lizards and Snakes • Belong to order Squamata (scaly reptiles) • Most lizards have legs, clawed toes, external ears, and movable eyelids • Some like the Gila have glands that produce venom • Snakes are legless, but very efficient predators • Vary in size – very small (size of earthworm) to very large like the python that grows up to 8 meters

18. Anoles

19. Lizards

20. Chameleon

21. Eastern Fence Lizard

22. Leaf-Tailed Gecko (Uroplatusfimbriatus)

23. Gila Monster Helodermasuspectum

24. Desert Iguana Dipsosaurusdorsalis

25. Green Tree Monitor Varanusprasinus

26. Five-Lined Skink Eumecesfasciatus http://www.jdmpics.com/lizard-pictures.htm

27. Crocodilians • Order Crocodilia • Includes alligators, crocodiles, caimans, and gavials • Long broad snout, and webbed feet • fierce carnivores that prey on animals such as fish, deer, and even humans • Crocodiles live only in warm tropical area in either fresh or salt water and are native to Africa, India, and Southeast Asia • Alligators live only in fresh water and are mostly found in North and South America • Alligators have a very broad, wide snout, and crocodiles have a narrower snout and jaw. Also crocodiles often have a lower tooth that juts out.

28. All species lay their eggs on land, near water but well above the water line. The eggs hatch anywhere from two to three months after being layed. Although the mother may lay as may as fifty eggs, few of the baby crocodilian will survive to adult hood. They are prey for many other animals, from birds to fish. http://www.flmnh.ufl.edu/cnhc/csl.html

30. Order Crocodilian • Differences Between Alligators and Crocodiles

31. Can you tell the difference between an alligator and a crocodile? C A B E F D

32. Order Crocodilian • Both Alligators and Crocodiles are… • Oviparous (egg-laying) • Guard nest and care for young • As with many turtles and some lizards – temperature of nest determines sex of young • Low temperature = females

33. Turtles and Tortoises • Order Testudines • Only reptiles that have a shell • Turtles live in water • Tortoises live on land • Terrapin a turtle that is found in salty water • Turtles and tortoises have a shell built into the skeleton • Two parts: • Ventral part is called plastron • Dorsal part is the carapace • Pull into shell to protect themselves • Wide range of habitats • Lack teeth but have horny ridges that cover upper and lower jaws • Strong limbs lift body off the ground when walking

34. Have been around for longer than dinosaurs (more than 200 million years)! • Most hibernate • Shed shell as they grow • http://www.photovault.com/Link/Animals/Reptiles/Turtles/ARTVolume01.html

35. Aldabra Tortoise Geochelonegigantia

36. Snapping turtle

37. http://www.photovault.com/Link/Animals/Reptiles/Turtles/ARTVolume01.htmlhttp://www.photovault.com/Link/Animals/Reptiles/Turtles/ARTVolume01.html

38. Tuataras • Only surviving member of order Sphenodonta and is found on a few small islands off coast of New Zealand • Resembles lizards but differ in that they do not have external ears and have a third eye which is part of the brain. • Live to be very old – more than 100 years!

39. Ecology of Reptiles • Many reptiles are in danger because their habitats are being destroyed • Humans hunt them for their skins and for food • Sea turtle programs are in place so that they can lay their eggs on beaches