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Class Amphibia. The Tetrapods. Moving Ashore. Transitional Forms. Early Land Tetrapods. Evolutionary Lung Forms. Changes in Lung Anatomy In Tetrapods. Amphibian Respiration. Changes in Vertebrate Circulatory Systems. Amphibian Heart Anatomy. General Amphibian Traits. • Tetrapods
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Class Amphibia The Tetrapods
General Amphibian Traits • Tetrapods • 3-5 digits on forelimb (most 4) • 5 digits on hind limb • No dermal scales • Glandular epidermis • Most with indirect development, some with tadpole larvae • Gills as larvae/juveniles, lungs present but may degenerate, some with dermal respiration
Order Gymnophiona • ~160 species • Legless • Burrowing or aquatic • Tropical • Internal fertilization • Oviparous & viviparous species • Direct development in most
Order Gymnophiona (Apoda) Caecilians
Order Caudata (Urodela) • AKA Salamanders • Have a tail • Divergence in respiratory mechanisms • Paedomorphosis prevalent • Internal fertilization
Some Urodeles Necturus maculosus Giant Japanese Salamander Southern dusky salamander Ambystoma mexicanum (Axolotl)
Order Anura • Frogs & Toads • No tail • External fertilization • Indirect development in most
Frog or Toad? • Frogs – Associated with more aquatic habitats • Toads – Thicker skins – Dryer habitats
Her Royal Highness • Xenopus laevis • Developmental model system
Really Weird Surinam Toad
Local Species Acris crepitans Rana catesbeiana Bufo speciosus Bufo woodhousii Pseudacris clarki Rana pipiens