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Amphibians

Amphibians. First Tetrapods on Land. Class: Amphibia. First truly tetrapod vertebrate Ectothermic All amphibians have bony skeletons Most have 4 limbs, except Caecilians (limbless) Many have webbed feet Typically the glandular skin is smooth, moist, and lacks scales

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Amphibians

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  1. Amphibians First Tetrapods on Land

  2. Class: Amphibia • First truly tetrapod vertebrate • Ectothermic • All amphibians have bony skeletons • Most have 4 limbs, except Caecilians (limbless) • Many have webbed feet • Typically the glandular skin is smooth, moist, and lacks scales • Metamorphose from juvenile water breathing to adult air breathing • Ecological indicators

  3. Order Anura (Salientia): Frogs and Toads • Order Caudata (Urodela): Salamanders, Newts, Waterdogs, Mudpuppies, Sirens, and Amphiuma • Order Gymnophiona (Apoda): Caecilians

  4. Class: Amphibia • Gas exchange occurs through lungs, gills, and/or the skin • Some salamanders have no lungs (secondarily lost) • Adults have double circulation • Both a pulmonary and a systemic circuit • Heart has three chambers • Two atria and one ventricle • Some mixing of oxygenated and deoxygenated blood occurs in ventricle

  5. Anamniotic egg http://epod.usra.edu/archive/images/egg_mass.jpg • Jellylike • unshelled; must develop in water • Small-sized • lack large membranes to nourish embryo and store waste Amphibian egg mass

  6. Amphibian development http://www.mybitoftheplanet.com/2002/ http://www.herpnet.net/Iowa-Herpetology/ Newt http://fwie.fw.vt.edu/VHS/ http://www.herpnet.net/Iowa-Herpetology/ Controlled by the hormone thyroxin

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