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 have vocal sacs in order to croak.
• Digestive system adapted to swallow prey whole
• Well developed muscular system

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Adaptations

• Four limbs with NO claws on digits (toes)
• Lungs instead of 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
• Necks to more easily see feed
• Most with smooth, moist skin to take in dissolved
  oxygen
• Some with oral glands to moisten food they eat
• Webbed toes without claws
• Ectothermic - body temperature changes with
  environment
• Show dormancy or torpor (state of inactivity
  during unfavorable environmental conditions)

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• Hibernate in winter and aestivate in summer
• Aquatic larva, called tadpole, goes through
  metamorphosis to adult
• Metamorphosis controlled by hormone called
  thyroxin

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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