The class Amphibia is composed of 3 orders: Anura (frogs and toads), the largest with over 3,500 species; Caudata (salamanders, newts, and sirens) with about 375 species; and Gymnophiona (caecilians) with about 160 species.

Last full review/revision July 2011 by Brent R. Whitaker, MS, DVM