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