1. Biology 11

2. Class Reptilia  Evolved from the amphibians and soon displaced them  Were much better adapted to land

3. Reptilia Objectives  General characteristics  Body systems: reproductive, respiratory, circulatory, nervous and skeletal  4 orders and example animals

4. General Characteristics 1. Amniotic egg – shelled 2. Internal fertilization 3. Scales or plates 4. If legs – 2 pair with claws, on ventral surface 5. Well developed lungs 6. Partial division of ventricle 7. Exothermic

5. Class Reptilia Characteristics and Advances: 1. Reproduction: A) The Amniotic Egg: reptiles solved the problem of water cased development with the amniotic egg. It allowed them to take water with them onto land for the development of the young B) Internal fertilization was now required

6. Amniotic egg  Shell – porous, prevents rapid water loss  Chorion – lines shell, gas exchange  Amnion – encloses embryo  Allantois – develops from embryo; carries on embryonic respiration and excretion  Yolk sac – contains food supply

7. Class Reptilia 2. Respiratory System:  Improved lungs no longer require skin for getting O 2 - skin can now dry out  Now they can cover skin with scales, shells or leathery layers

8. Class Reptilia 3. Circulatory system  Activity levels required more oxygenated blood - the three and a half chambered heart  The ventricle was almost completely separated so that the right side of the heart pumps to the lungs and the left to the body  BUT still some mixing!

11. Class Reptilia 4. Nervous system:  Better senses developing along with a larger brain, better land adaptation  Cerebrum and cerebellum continue to increase in size

12. Class Reptilia 5. Behaviours  Bigger brain and internal fertilization result in specific behaviors Mate selection behaviors Mate selection behaviors Territoriality Territoriality  This tended to increase contribution of best fit males to gene pool

13. Class Reptilia 6. Skeletal Skeletal  Appendages grow out from ventral side of reptiles raising their body off the ground - not belly draggers  Allows for better and faster movement on land

14. Class Reptilia Evolution  Reptiles reached their evolutionary climax in the Mesozoic with the dinosaurs.  They were the dominant vertebrate life for over 200 million years!

15. Class Reptilia  Evidence suggests that the Mesozoic ended with a bang - as a large meteorite or comet struck the Earth  This first brought on intense heat, followed by at least a ten year global winter  95% of all life went extinct during this very short time frame including the trilobites

16. Class Reptilia  However, the Earth was changing anyway becoming cooler, drier, and more unstable  This favored adaptations that allowed survival in these conditions  Small isolated pockets of reptiles adapted and survived the end of the Mesozoic

17. Modern Day Reptiles  Order Rhynchoephalia: Tuatara (Sphenodon)  Order Chelonia: Turtles  Order Crocodilia: Crocs and gators  Order Squamata: Snakes and lizards

18. Order Rhynchoephalia  Tuatara (Sphenodon) – only living example  Found in New Zealand  Resembles large lizard  Parietal eye – third eye covered by skin; senses sun’s radiation

19. Order Chelonia  Turtle – sea turtles 230 species 230 species Webbed feet Webbed feet Soft-shelled (streamlines) Soft-shelled (streamlines) Omnivorous Omnivorous

20. Order Chelonia  Terrapin – fresh water turtles Claws and webbed feet Claws and webbed feet Symmetrical plates called scutes covering bony under layers Symmetrical plates called scutes covering bony under layers Top shell – carapace Top shell – carapace Bottom shell - plastron Bottom shell - plastron

21. Order Chelonia  Tortoise – land turtle Long necks, short limbs Long necks, short limbs Appendages completely drawn into shell, if not – very aggressive Appendages completely drawn into shell, if not – very aggressive No teeth No teeth Tympanic membrane (poor hearing) Tympanic membrane (poor hearing) Good sense of smell Good sense of smell Good color vision Good color vision Temperature determines sex of eggs: low temp = males Temperature determines sex of eggs: low temp = males

22. Order Crocodilia  Only reptile with a 4 chambered heart  Carnivorous  Raised nostrils and eyes (so rest of body is underwater)  Valve at back of mouth prevents water from entering lungs when mouth is open

23. Order Crocodilia AlligatorsCrocodiles Less aggressive More aggressive More terrestrial More aquatic Rectangular head Triangular head Teeth not visible when mouth is closed Teeth visible when mouth is closed Definite vocalizations No definite vocalizations

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

25. Order Crocodilian  Both Alligators and Crocodiles… Guard nest and care for young Guard nest and care for young As with many turtles and some lizards – temperature of nest determines sex of young As with many turtles and some lizards – temperature of nest determines sex of young ○ Low temperature = females

26. Order Squamata – Lizards/Snakes  Moveable eyelids  See color (except geckos)  External ear  Vocalize  Live in arid climates, conserve water by excreting uric acid (white paste that is the pre-cursor to urine)

27. Lizards  Iguanas – horned toad  True chameleons – change color in response to light, temperature and mood; arboreal (tree dwelling); tongue longer than body

28. Lizards  Gila Monster (aka Beaded Lizard) – only poisonous lizard known to the world Native to the desert southwest of the US and Mexico Native to the desert southwest of the US and Mexico Poison is found in saliva… no fangs! Poison is found in saliva… no fangs! The poison is a nerve toxin, that is produced in glands located in the lower jaw. When a Gila Monster bites an animal, the poison flows into the wound via grooved teeth. This poison only rarely kills people. The poison is a nerve toxin, that is produced in glands located in the lower jaw. When a Gila Monster bites an animal, the poison flows into the wound via grooved teeth. This poison only rarely kills people. Gila Monster Beaded Lizard

29. Lizards  Gecko (Geico?) – most primitive; pads on toes to cling; makes noises, insectivores, eye has vertical pupil to see at night

30. Lizards  Monitor – Komodo Dragon is largest = 10 feet FYI: The Komodo Dragon is not venomous or poisonous; however, its saliva contains a number of toxic strains of bacteria which often infect the wounds inflicted on its prey, causing death. FYI: The Komodo Dragon is not venomous or poisonous; however, its saliva contains a number of toxic strains of bacteria which often infect the wounds inflicted on its prey, causing death.

31. Snakes  Loss of limbs and external ears  Evolved from lizards  Most numerous reptile  2,800 species (300 poisonous)

33. Snake Feeding  Carnivorous  Kills via: Poison or constriction  Swallow food whole Jaw comes unhinged Jaw comes unhinged Elastic ligaments Elastic ligaments Glottis moves forward (so can breathe while swallowing) Glottis moves forward (so can breathe while swallowing) Large esophagus Large esophagus No sternum No sternum Strong stomach acid Strong stomach acid

34. SnakesNon-Poisonous:  Garter snake  Black snake  King snake  Boa constrictor Poisonous:  Vipers Rattlesnakes, copperheads, adder Rattlesnakes, copperheads, adder  Elapsids (cause swelling of lymph nodes) Cobras, coral, kraits Cobras, coral, kraits Rattlesnake Garter

35. Non-Poisonous Boa Black King Garter

36. Poisonous Snakes Copperhead Puff Adder Rattlesnake Cobra Coral Snake Krait

37. Snake Venom

38.  Neurotoxin – affect nervous system  Hemotoxin or hemmoragin – affects red blood cells  All contain both types, the amounts of each may differ  Danger is in the amount and concentration of injected venom and where its injected: In blood vessel… spread fast In blood vessel… spread fast In muscle or fat… spread slow In muscle or fat… spread slow

39. Top Ten Most Deadly Snakes 1) Fierce Snake or Inland Taipan (Oxyuranus microlepidotus), Australia. 2) Australian Brown Snake (Pseudonaja textilis), Australia. 3) Malayan Krait (Bungarus candidus), Southeast Asia and Indonesia. 4) Taipan (Oxyuranus scutellatus), Australia. 5) Tiger Snake (Notechis scutatus), Australia.. 6) Beaked Sea Snake (Enhydrina schistosa), South Asian waters Arabian Sea to Coral Sea. 7) Saw Scaled Viper (Echis carinatus), Middle East Asia. 8) Coral Snake (Micrurus fulvius), North America. 9) Boomslang (Dispholidus typus), Africa. 10) Death Adder (Acanthophis antarcticus), Australia and New Guinea.