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Amphibians. Amphibia. Comes from the Greek amphi “both” and bios “life” Appeared during the Devonian period. Adaptations. Four limbs Lungs instead of gills Both internal & external nares (nostrils) Three chambered heart (two atria & one ventricle).
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Amphibia • Comes from the Greek amphi “both” and bios “life” • Appeared during the Devonian period
Adaptations • Four limbs • Lungs instead of gills • Both internal & external nares (nostrils) • Three chambered heart (two atria & one ventricle)
Skin with keratin (protein) to prevent water loss • Most with smooth, moist skin to take in dissolved oxygen • Some with oral glands to moisten food they eat
Ectothermic - body temperature changes with environment • Show dormancy or torpor (state of inactivity during unfavorable environmental conditions) • Hibernate in winter and aestivate in summer • Males with vocal sacs to croak • Digested system adapted to swallow prey whole • Well developed muscular system
Anura • Frogs • Toads
Characteristics • Both terrestrial & freshwater species • Tadpole with tail, gills, & two-chambered heart • Adults without a tail, four limbs, & lungs • Frog skin smooth & moist for cutaneous respiration, while toads is rough & warty (poison glands)
Aquatic larva called tadpole goes through metamorphosis to adult • Metamorphosis controlled by hormone called thyroxine
Reproduction • 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
Caudata • Newts and Salamanders
Characteristics • Have elongated bodies with a tail & four limbs • Smooth, moist skin for cutaneous respiration • Size from a few centimeters long to 1.5 meters • Nocturnal when live in drier areas • Newts are aquatic species
Lay eggs in water or damp soil • Some bear live young • May or may not go through tadpole stage (some hatch & look like small adult) • All newts are salamanders but not all salamanders are newts
Apoda • caecilians
Tropical, burrowing, worm like amphibians • Legless • Small eyes & often blind • Eat worms & other invertebrates • Average length 30 centimeters, but can grow up to 1.3 meters • internal fertilization • Female bear live young