Chapter 20-Reptiles

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Chapter 20-Reptiles

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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

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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

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Sun Basking
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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

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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

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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

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Reptilian Heart Structure
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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

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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

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Order Squamata/Suborder Sauria- Lizards

• Mostly small (lt30 cm)
• Largest Kimodo dragons (lt3 m)
• Tail may break off to avoid predation
  (regenerates w/no vertebrae)
• Molt skin periodically
• Include
• Iguanas
• Chameleons
• Geckos
• Anoles
• Horned lizards
• Monitors
• Skinks

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

• Several hundred vertebrae
• Jacobsons 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
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Order Squamata/Suborder Serpentes/Family Boidae-
Constrictor Snakes
Anaconda
Emerald tree boa
Banded king snake
Scarlet king snake
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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

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Order Squamata/Suborder Serpentes- Venomous
Snakes
Coral snake
King cobra
Krait
Sea snake
Puff adder
Eyelash viper
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Order Squamata/Suborder Serpentes- Venomous Snakes
Water mocassin (a.k.a. Cottonmouth)
Copperhead
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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

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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

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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 teethpowerful beak
• Many herbivores some carnivores

Giant tortoise
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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
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Order Crocodilia- Alligators, Crocodiles,
Caimans, and Gavials
Caiman

• 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
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Order Crocodilia- Alligators, Crocodiles,
Caimans, and Gavials
American alligator
Nile crocodile
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Order Rhynchocephalia- Tuataras

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