The 80-odd species of Texas' frogs, toads and salamanders are the modern representatives of the vertebrate class Amphibia, which has been around for some 350 million years. Amphibians were the first vertebrates to exploit terrestrial environments in more than a casual way, preceded of course by plants and insects.
Most amphibians reproduce by laying eggs.
Amphibians have successfully exploited this strategy of utilizing quite different environments at different times during their life-histories, and today occur on every continent except Antarctica. They are the dominant vertebrates in some habitats, both in the number of species and the number of individuals present. Texas has a diverse set of species, the greatest abundance and diversity in the relatively wet habitats of the eastern third of the state. Many salamanders, such as the sirens, amphiumas, waterdogs, and spring salamanders of the genus Eurycea, never metamorphose and spend all their lives in water. Some frogs, such as the true frogs of the genus Rana, are basically tied to permanent wetlands whereas others, like the treefrogs belonging to the genera Acris, Hyla and Pseudacris, can use more ephemeral wetlands.