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Class Reptilia

Class Reptilia. 1. 2. History. Reptiles are the evolutionary base for the rest of the tetrapods . Early divergence of mammals from reptilian ancestor. Early reptiles arose from amphibian ancestor and were small, lizard-like insectivores . 3. Class Reptilia. Scales Amniotic egg

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Class Reptilia

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  1. Class Reptilia 1

  2. 2

  3. History • Reptiles are the evolutionary base for the rest of the tetrapods. • Early divergence of mammals from reptilian ancestor. • Early reptiles arose from amphibian ancestor and were small, lizard-like insectivores. 3

  4. Class Reptilia • Scales • Amniotic egg • One occipital condyle • Ectothermic • Three chambered heart • Alligators have 4 • Claws 4

  5. Ectothermic 5

  6. Common Features • Positioning of legs more directly under animal (more support). • Paired limbs with five toes. • Adapted for running, climbing, swimming. • Absent in snakes. 6

  7. Common Features • Body covered with horny epidermal scales made from protein keratin. • Scales serve to reduce water loss and provide protection. • Reptiles molt as they grow. • Jaws adapted to biting/tearing. 7

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  9. Common features • Respiration through internally protected and moistened (a moist cloacal surface in some turtles). • Most reptiles have a 3-chambered heart with a partially divided ventricle. • No mixing of blood from lungs with deoxygenated blood. • Crocodiles have 4 chambers and a unique feature: cog teeth. 9

  10. Common features • Excretory waste = uric acid (doesn’t waste water) • Brain = first cerebral cortex (capable of reasoning, planning, perception) • Still ectothermic • Must live in favorable conditions or hibernate. • Being ectothermic enables an organism to survive on much less food than an endothermic organism. 10

  11. Reproduction • Internal fertilization: gametes not subject to desiccation. • Amniote egg = significant evolutionary breakthrough. • Egg covered by tough, water-resistant, leathery or calcerous shell. • Extraembryonic membranes compartmentalize the interior for several functions. 11

  12. Amniote Egg 12

  13. Amniote Egg • Chorion = hard covering permeable to respiratory gases but not water. • Allantois = functions in gas exchange and a storage reservoir for metabolic waste. • Amnion = fluid-filled sac acts as cushion for embryo and prevents desiccation. • Yolk sac = food for embryo; eliminates need for larval stage. 13

  14. Reptile Skulls • Except for turtles, all reptiles have two temporal openings in the skull. • These openings have allowed for attachment and expansion of the jaw muscles. 14

  15. Reptile Skulls • Anapsid • No opening • Synapsid • One opening • Diapsid • Two openings • Euryapsid • One small opening 15

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  17. Subclass AnapsidaOrder Testudines • 260 species of turtles/tortoises • Oldest group of reptiles (225 mya) • Protective body shell • Encases vital organs • Provides some protection to head/limbs • Composed of bony plates covered by horny epidermal scales • 2 parts: upper carapace, lower plastron 17

  18. Primitive features • Loss of body-wall muscles • Ribs/trunk vertebrae fused to carapace • Lack teeth; hard beak grab and tear food

  19. Subclass AnapsidaOrder Testudines • All lay eggs on land. • Third eyelid = nictitating membrane. • Longest living vertebrates (100+years in wild)! 19

  20. TURTLES & TORTOISES • Only reptile with shell • Only reptile WITHOUT TEETH 20 http://www.perlgurl.org/archives/2006/05/hawaiian_honu_the_green_sea_turtle.html http://www.carcosa.net/jason/blog_images/2005/07/04/african-spurred-tortoise.jpg

  21. Turtle Shell Carapace 21 Plastron

  22. 22

  23. Adapted to live on land Feet not webbed High domed shell Safe Box TurtleTerrapene 23

  24. Red stripe behind eye Live in or near water Ponds Slow moving water Pets Carry Salmonella Red-Eared SliderTrachemys 24

  25. Live in water Lay eggs on land Long tail Muscular limbs Snapping TurtleChelydra 25

  26. 26

  27. Giant TortoiseLifespan 150 Years 27

  28. Leatherback Sea Turtle • 6 feet long • 1,400 pounds 28

  29. Diapsids • Dinosaurs • Snakes • Lizards • Crocodilians • Birds 29

  30. Subclass Diapsida • Superorder Lepidosauria • Order Squamata • 4675+ species of lizard • 2700+ species of snakes • 140 species of amphisbaenians • Limbless, burrowing animals • Vestigial eyes under skin 30

  31. Order Rhynchocephalia • 2 species of Tuatara • Solitary, nocturnal, burrowing animal

  32. Order Squamata • Kinetic skull • Movable joints • Lizards • Snakes • Dinosaurs 32

  33. Order Squamata • Most successful, diversified of living reptiles. • Occur in most habitats of world. • Lizards: • Legs, eyelids, ear openings • Halves of lower jaw united 33

  34. Geckos • Small lizards • Adhesive toe pads 34

  35. Gecko Toe Pads 35

  36. Wall LizardLacerta • Color is variable • Slender body • Small scales 36

  37. AUTOTOMY • Self amputation to escape predators • Can’t regrow • Costly; lose muscle/stored fat 37 http://www.californiaherps.com/lizards/images/ecprincipis1dn.jpg

  38. Texas Horned Lizard • Spines for protection • Eats ants • Endangered species 38

  39. Gila Monster • Poisonous lizard • Not very aggressive 39

  40. Green Iguana • Ornamental crest • Five feet long • Tropical rainforest • Mexico • South America • Omnivores 40

  41. Chameleons • Arboreal - live in trees • Africa and Madagascar • Catch insects with tongue 41

  42. Komodo Dragon • Attack and eat humans • 10 feet long • 300 pounds • Indonesia 42

  43. Snakes • Elongated derivative of lizard (increased vertebrae, not lengthening of segments) • Lack limbs, eyelids, ear openings • Jaw bones are loosely united to allow swallowing of large prey • Throat and windpipe are at separate ends of mouth to allow breathing while eating • Can be venomous (hemotoxin/neurotoxin) • Tongue to smell, some have heat pits to sense body heat

  44. Snakes • No legs • No external ears • Jacobson’s organ • Sense smell with aid of tongue • Cornea of eye protected with a spectacle • transparent membrane • Skull bones loose • Swallow large prey 44

  45. JACOBSON’s ORGAN • An extrasensory organ in the roof of a snake's mouth • Sharpens its sense of smell. • Two hollow, highly sensitive saclike structures • Allows it to track both prey and potential mates 45 http://www.kwic.com/~pagodavista/schoolhouse/species/herps/snktonge.htm

  46. HEAT SENSING ORGAN • “Pit" organ located between the eye and the nostril on each side of the head. • Detects heat given off by warm-blooded prey 46 http://www.kwic.com/~pagodavista/schoolhouse/species/herps/snktonge.htm

  47. Swallow Prey 47

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  49. http://www.thematzats.com/snakes/images/squeeze.gif Constrictors • Wrap around prey and kill by suffocation • Ex: Boa constrictors 49 http://www.eastrock.org/brazil/images/bra19.jpg

  50. VIPERS • Inject venom with large movable fangs Ex: rattlesnakes, copperheads, water moccasins 50 Images from: http://www.worsleyschool.net/science/files/rattle/snakes.html

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