Amphibians (class Amphibia), such as frogs, toads, salamanders, newts, and gymnophiona, are cold-blooded animals that metamorphose from a juvenile, water-breathing form to an adult, air-breathing form. Typically, amphibians have four limbs. Unlike other land animals (amniotes), amphibians lay eggs in water, as their fish ancestors did. Amphibians are superficially similar to reptiles.
Amphibian populations around the globe are threatened or extinct, and scientists do not agree on the reason.
Amphibians evolved in the Devonian Period. They were a top predator in the Carboniferous Period.