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Chapter 20-Reptiles

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1 Chapter 20-Reptiles

2 Class Reptilia Snakes, lizards, skinks, turtles, and crocodilians
Strong, bony skeleton and toes w/claws Ectothermic metabolism Dry, scaly skin Amniotic eggs Respiration through well-developed lungs Ventricle of heart partly divided by a septum Internal fertilization

3 Ectothermic Metabolism
Metabolism too slow to generate own body heat Intolerance to cold-become sluggish and unable to function Absorb heat from environment Basking in sun to heat up Shade to cool down Maintain relatively constant by alternating

4 Sun Basking

5 Water Retention Overlapping Scales
Do not lose water through skin or require water to reproduce like amphibians Skin -light and flexible scales Overlapping minimizes water loss Enables reptiles to live in dry environments

6 Watertight Eggs Amniotic Eggs Fertilized eggs need moisture to develop
Internal fertilization allows for moisture to surround eggs Amniotic egg- Tough-shelled egg containing a water and food supply Most reptiles All birds Some mammals

7 Respiration Lungs w/many folds increase gas exchanging surface
Strong muscles attach to rib sage aid expansion and contraction of lungs Incomplete septum separates ventricle of heart Crocodilians have completely divided ventricle Complete septum separates atrium of heart More separation of oxygen-rich and oxygen-poor blood Oxygen delivered to body cells more efficiently

8 Reptilian Heart Structure

9 Reproduction Internal fertilization- Male introduces semen directly into females body Protects gametes from drying out Oviparous (most)- Young hatch from eggs Most cases parents do not protect Ovoviviparous (some)- Female retains eggs in body until just before hatching; sometimes hatching occurs in mother Eggs less vulnerable to predation Nourishment of eggs from yolk

10 Order Squamata Includes lizards and snakes
Lower jaw loosely connected to skull Mostly carnivores; some herbivores Mouth opens wide to accommodate prey Extremely successful predators

11 Order Squamata/Suborder Sauria- Lizards
Mostly small (<30 cm) Largest: Kimodo dragons (<3 m) Tail may break off to avoid predation (regenerates w/no vertebrae) Molt skin periodically Include: Iguanas Chameleons Geckos Anoles Horned lizards Monitors Skinks

12 Order Squamata/Suborder Sauria- Lizards
Green Iguana Veiled chameleon Leopard Gecko Anole Texas horned lizard Nile monitor

13 Order Squamata/Suborder Serpentes- Snakes
Gaboon viper Legless w/no eyelids nor external ears No pectoral girdle Five-point movement in jaw Elastic ligament allows lower jaw to spread No chewing or cutting teeth Ovoviviparous 2/3 in family Colubridae and non-venomous Green tree python

14 Order Squamata/Suborder Serpentes- Snakes
Several hundred vertebrae Jacobson’s Organs- Depressions in roof of mouth detect smell Feeding: All snakes subdue prey and swallow whole Constrictors squeeze prey until suffocation Anacondas, boas, pythons, and king snakes Ball python

15 Order Squamata/Suborder Serpentes/Family Boidae- Constrictor Snakes
Anaconda Emerald tree boa Banded king snake Scarlet king snake

16 Order Squamata/Suborder Serpentes- Snakes
Venomous snakes Modified salivary glands produce venom to inject into prey with grooved or hollow teeth Families: Elapidae- Cobras, kraits, mambas, taipans, and coral snakes Hydrophiidae- Sea snakes Viperidae- Rattlesnakes, moccasins, adders, vipers and copperheads

17 Order Squamata/Suborder Serpentes- Venomous Snakes
Coral snake King cobra Krait Sea snake Puff adder Eyelash viper

18 Order Squamata/Suborder Serpentes- Venomous Snakes
Water mocassin (a.k.a. Cottonmouth) Copperhead                                         

19 Order Squamata/Suborder Serpentes- Rattlesnakes
Rattle- 5 to 7 rings of keratin and protein New ring each molt Pit organ- Openings between eye and nostril detect infrared Venom- Hemotoxin affects red blood cells causing hemorrhaging Timber rattlesnake Diamondback rattlesnake

20 Order Squamata/Suborder Amphisbaenia- Worm Lizards
~ 135 species Amphis – double; baen – to walk Move easily backwards and forwards Burrowers Unique single median tooth on upper jaw Annuli – ring-like folds in skin Oviparous – Feed on worms and small insects

21 Order Chelonia (Testudines)- Turtles and Tortoises
Gopher tortoise 250 species Body encased in shell Bony plates covered w/leathery skin Vertebrae fused to dorsal Provides support for muscles Some for protection Carapace- dorsal part of the shell Plastron- Ventral No teeth;powerful beak Many herbivores; some carnivores Giant tortoise

22 Order Chelonia (Testudines)- Turtles and Tortoises
Alligator snapping turtle Turtles- Stream-lined, disk-shaped shell for water movement Tortoises- Dome- shaped shell Box turtle Sea turtle

23 Order Crocodilia- Alligators, Crocodiles, Caimans, and Gavials
Large aggressive carnivores Capture prey by stealth, drowns, and eats Eyes and nostrils on top of head to allow for seeing and breathing while under water Strong neck w/large mouth (100s of sharp teeth) Throat valve prevents water entering into lungs Uniquely care for young after hatching Gavial

24 Order Crocodilia- Alligators, Crocodiles, Caimans, and Gavials
American alligator Nile crocodile

25 Order Rhynchocephalia- Tuataras
Native to New Zealand Lizard-like Uniquely active at low temp./night Unchanged for 150 million yrs. 2 species Genus Sphenodon

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