Phylum Chordata Subphylum vertebrata Class reptilia

1. Biology 11 Phylum ChordataSubphylum vertebrata Class reptilia

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 • Amniotic egg – shelled • Internal fertilization • Scales or plates • If legs – 2 pair with claws, on ventral surface • Well developed lungs • Partial division of ventricle • 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 fertilizationwas 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 O2 - 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 • Territoriality • This tended to increase contribution of best fit males to gene pool

13. Class Reptilia 6. 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 • Webbed feet • Soft-shelled (streamlines) • Omnivorous

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

21. Order Chelonia • Tortoise – land turtle • Long necks, short limbs • Appendages completely drawn into shell, if not – very aggressive • No teeth • Tympanic membrane (poor hearing) • Good sense of smell • Good color vision • 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

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

25. Order Crocodilian • Both Alligators and Crocodiles… • Guard nest and care for 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. Gila Monster (aka Beaded Lizard) – only poisonous lizard known to the world Native to the desert southwest of the US and Mexico 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. Lizards 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.

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 • Elastic ligaments • Glottis moves forward (so can breathe while swallowing) • Large esophagus • No sternum • Strong stomach acid

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

35. Black Non-Poisonous Boa Garter King

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

37. Snake Venom

38. Snake Venom • 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 muscle or fat… spread slow

39. Top Ten Most Deadly Snakes 1) Fierce Snake or Inland Taipan(Oxyuranusmicrolepidotus), Australia. 2) Australian Brown Snake (Pseudonajatextilis), Australia. 3) Malayan Krait (Bungaruscandidus), Southeast Asia and Indonesia. 4) Taipan(Oxyuranusscutellatus), Australia. 5) Tiger Snake (Notechisscutatus), Australia.. 6) Beaked Sea Snake (Enhydrinaschistosa), South Asian waters Arabian Sea to Coral Sea. 7) Saw Scaled Viper (Echiscarinatus), Middle East Asia. 8) Coral Snake (Micrurusfulvius), North America. 9) Boomslang(Dispholidustypus), Africa. 10) Death Adder (Acanthophisantarcticus), Australia and New Guinea.