Part lll : Animals

Reptiles & Amphibians


Terrestrial Adaptations:

  • Toes with claws to dig & climb

  • Dry, watertight skin covered by scales to prevent desiccation (water loss)

  • May bask or lie in sun to raise body temperature or seek shade to lower body temperature; known as thermoregulation

  • Ectothermic - body temperature controlled by environment

  • Snakes use scales & well developed muscular & skeletal systems to move

  • Geckos have toes modified into suction cups to aid climbing


  • Lungs for respiration

  • Double circulation of blood through heart to increase oxygen to cells

  • Water conserved as nitrogen wastes excreted in dry, paste like form of uric acid crystals

  • Partial separation in ventricle to separate oxygenated & deoxygenated blood


  • Amniotic Egg
  • Protective membranes & porous shell around embro
  • Shell leathery & waterproof
  • Internal fertilization before shell is formed


  • Both internal and external nares (nostrils)
  • Lungs instead of gills
  • Double loop blood circulation to lungs and rest of body cells
  • Four limbs with claw on digits (toes)
  • Three chambered heart (two atria and one ventricle)
  • Necks help to see much easier and to feed
  • Skin with keratin (protein) to prevent water loss


  • Ectothermic - body temperature changes with environment
  • Show dormancy or torpor (state of inactivity during unfavorable environmental conditions)
  • Most with smooth, moist skin to take in dissolved oxygen
  • Some with oral glands to moisten food they eat
  • Hibernate in winter and aestivate in summer
  • Webbed toes with claws
  • Aquatic larva called tadpole goes through metamorphosis to adult Metamorphosis


  • External fertilization with amplexus (male clasps back of female as sperm & eggs deposited into water

  • Eggs coated with sticky, jelly like material so they attach to objects in water & do not float away

  • Well developed muscular system

  • Digested system adapted to swallow prey whole

  • Males with vocal sacs to croak

  • Eggs hatch into tadpoles in about 12 days

Animal Reptiles and Amphibians

Resources :

  • A Field Guide to Western Reptiles and Amphibians, by Robert C Stebbins (2003)
  • The National Audubon Society Field Guide to North American Reptiles and Amphibians by John L. Behler and F, Wayne King.
  • A Field Guide to Reptiles & Amphibians: Eastern and Central North America, by Roger Conant and Joseph T. Collins (1998),