48 species of amphibians (class Amphibia) are known to inhabit the state of West Virginia. The ranges of some 34 salamander species and 14 species of frogs and toads extend into some portion of the state. Two of these — the Cheat Mountain salamander and West Virginia spring salamander — are endemic to West Virginia; they are the only vertebrate species found only within the state. The former species is considered threatened and the latter is considered endangered by federal authorities. Many of West Virginia's amphibian species are declining in population due to habitat destruction and water pollution.