Phylum Chordata - Chordates Internal skeleton with muscle ...

Class Amphibia - Amphibiansincludes frogs, salamanders, caeciliansAmphibians were the first “tetrapods”the first terrestrial vertebratesThere are three orders of AmphibiansOrder Anura - frogs and toadsOrder Urodela - salamandersOrder Apoda - caeciliansCharacteristics of AmphibiansLegs - a key adaptation for terrestrial livingFrog and salamanders have two pairs, lost in caeciliansLungs - a modified swim bladder used for terrestrial respirationswallow air by moving floor of mouthCutaneous respiration - gas exchange at skinsupplement lung respiration with a highly vascularized skinMoist skin provides extensive surface area, limits body size