Amphibians

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Amphibians
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Classification

• Anura - frogs toads
• Urodela - salamanders newts
• Apoda - caecilians
• Trachystoma - sirens or mud eels

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Amphibian Basics

• Amphibians are ectothermic (animal whose body
  does not produce much internal heat) vertebrates
  that spend early life in water
• The word Amphibian means double life.
• After starting their lives in water Amphibians
  spend their adulthood on land.

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Frogs

• Males with vocal sacs to croak
• Digested system adapted to swallow prey whole
• Some with oral glands to moisten food they eat
• Well developed muscular system

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Adaptations

• Four limbs
• Lungs and gills
• Both internal external nares (nostrils)
• Three chambered heart (two atria one ventricle)
• Double loop blood circulation to lungs rest of
  body cells

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• Skin with keratin (protein) to prevent water loss
• Eyes to more easily see feed
• Most with smooth, moist skin to take in dissolved
  oxygen
• Webbed toes without claws
• Show dormancy or torpor (state of inactivity
  during unfavorable environmental conditions)
• Hibernate in winter and aestivate in summer

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• Aquatic larva called tadpole goes through
  metamorphosis to adult
• First develop hind legsgt Lungs/Front legsgt gills
  disappear and tail slowly grows shorter
• Metamorphosis controlled by hormone called
  thyroxine

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Tadpole

• 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
• Eggs hatch into tadpoles in about 12 days

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Tadpole
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Reptiles
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Reptile Characteristics

• Ectothermic body temperature determined by
  environment
• Two pairs of legs four limbs
• Obtain oxygen from the air by using lungs
• Sensory organs adapted for use on land
• Lay eggs, with shells on land
• Lungs not gills

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Reptile Examples

• Snakes
• Turtles
• Alligators
• Crocodiles
• Geckos
• Lizards
• Iguanas