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Reptiles

Reptiles. Nonavian Diapsid Amniotes. Taxonomy. Kingdom: Animalia Phylum: Chordata Subphylum: Craniata Infraphylum : Vertebrata Class: Reptilia. Evolutionary Adaptations. Evolved ~ 350 mya Able to live on land….thanks to the amniotic egg. Amniotic Egg

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Reptiles

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  1. Reptiles NonavianDiapsid Amniotes

  2. Taxonomy • Kingdom: Animalia • Phylum: Chordata • Subphylum: Craniata • Infraphylum: Vertebrata • Class: Reptilia

  3. Evolutionary Adaptations • Evolved ~ 350 mya • Able to live on land….thanks to the amniotic egg • Amniotic Egg • Extraembryonic membranes to… • Protect the embryo from desiccation (drying out) • Cushion the embryo • Promote gas transfer • Store waste materials • Leathery or hard shells for protection • Albumen for cushion, moisture, & nutrients • Yolk supplies the food

  4. Reptile Adaptations to… Life on Land • Amniotic Egg • Impervious skin • Horny nails- used for digging & locomotion • Water-conserving kidneys • Enlarged lungs • Loss of lateral-line system

  5. Reptile Characteristics • Thick, dry, & keratinzed skin (covered in scales) • May secrete pheromones through their skin for sex recognition & defense • Shed their skin (ecdysis) • Due to low blood flow to the outer layer of skin • Skin may be colored for sex recognition, mimicry, and for cryptic purposes

  6. Reptile Characteristics • Skeleton: • Longer skull- development for breathing and better smell • More cervical vertebrae for head movement • Ribs modified • Fused to create the shell in turtles • Muscular connections for movement in snakes • Tail vertebrae may possess a fracture plane • Can break their tail off when threatened

  7. Reptile Characteristics • Nutrition & Diet • Carnivores • Except turtles (may be carnivores, herbivores, or omnivores) • May have sticky tongues for catching prey • May extend the length of their body • Skull and jaw bones may spread apart to allow room for bigger prey

  8. Reptile Characteristics • Circulation, Gas Exchange, & Temperature Regulation • 3 chambered heart • 2 atria & 1 ventricle • Ventricle is partially divided (completely divided in crocodiles) • Breathe with lungs • Thermoregulate with external heat sources (ectothermic) • Tend to bask in sunlight for warmth

  9. Reptile Characteristics • Nervous System • Developed brain • Vision is the dominant sense • Upper & lower eyelids and nictitating membrane • May detect light with a median (parietal) eye • Jacobson’s (vomeronasal) organs- olfactory organs • Connected to the forked tongues in snakes

  10. Reptile Characteristics • Reproduction & Development • Dioecious • Internal fertilization • Sex organs contained inside of the cloaca • Courtship behavior is species specific • Mother abandons eggs after she lays them • Alligator nest temperature determines gender of young • <31.5C= females • 32.5-33C= males • 32C= males & females

  11. Class: ReptiliaOrder: Testudines Carapace • Turtles • Characteristics: • Bony shell • Limbs articulating internally to the ribs • Keratinized beak rather than teeth • Shell • Dorsal=carapace • Ventral=plastron Plastron

  12. Class: ReptiliaOrder: Testudines • North American box turtle • Shell has hinges to allow the anterior & posterior regions to raise up or down • The shell closes when the turtle pulls in it’s head & tail

  13. Class: ReptiliaOrder: Testudines • Long life spans • Large tortoises live >100 years • Reach sexual maturity between 7 & 8 years • Oviparous- lay eggs • Females dig out nests in the soil • Cover the 5-100 eggs with soil • Eggs take 4 weeks to 1 year to develop • Young are independent from parents (no parental care)

  14. Class: ReptiliaOrder: Testudines • Turtles vs. Tortoises • Turtles- aquatic & have webbed feet • Tortoises- terrestrial & do not have webbed feet • Conservation • Turtles are vulnerable due to… • Slow growth rates • Long juvenile periods • Nearing extinction thanks to young turtle predators & turtle hunters

  15. Class: ReptiliaOrder: Crocodylia • Alligators, crocodiles, gavials, & caimans • Derived from archosaurs (ancient reptiles) • Triangular eye orbits • Laterally compressed teeth • Mildly evolving over the past 170 my • Nostrils are at the tip of the snout (can breathe while mostly submerged) • Muscular & elongated tail • Swimming, offense, defense, & attacking prey • Swallow food whole • Oviparous & take care of their young

  16. Class: ReptiliaOrder: Squamata • Lizards • 2 pairs of legs • Upper & lower jaws unite anteriorly • Geckos- nocturnal & can vocalize with clicking sounds • Iguanas- can glide from a tree for at least 30 m • Chameleons- arboreal & consume insects • Change color in response to illumination, temperature, & behavioral state • Gila monster- venomous lizard • Southwest U.S. • Venom released when they chew (not fatal to humans)

  17. Class: ReptiliaOrder: Squamata • Snakes • 2,900 species (300 are venomous…not poisonous!!!) • Scale patterns can determine whether the snake is venomous or not • 30,000 people die a year from snake bites (mostly in SE Asia) • Only 9-15 die from snake bites each year in the U.S. • Long & lack limbs • May contain more than 200 vertebrae • May swallow large prey whole (movable jaw)

  18. Class: ReptiliaOrder: Squamata • Worm Lizards • Live in the soils of Africa, South America, the Caribbean, & the Mideast • Legless • Single median tooth in the upper jaw • Ringlike folds in the skin (annuli) • Easily move forwards or backwards

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