Species can be arboreal, fossorial (burrowing), or semiaquatic. They occupy aquatic, arboreal, terrestrial and fossorial environments. Blind skinks are characterized by their fossorial or burrowing habits. Various species are respectively terrestrial, arboreal, or fossorial. More species are terrestrial or fossorial (burrowing) than arboreal (tree-climbing) or aquatic species. The martens, fisher and tayra are partially arboreal, while badgers are fossorial. It feeds primarily on specific snakes, probably semiaquatic and fossorial snakes. Madagascan burrowing frogs are less fossorial and mostly bury themselves in leaf litter. The American spadefoot toads are of typical shape to most fossorial (or burrowing) frogs. The tree frogs of Australia have various habits, from completely arboreal to fossorial. The pink fairy armadillo is classified as a fossorial generalist insectivore. All are fossorial (adapted for burrowing). Scarlet kingsnakes are secretive, nocturnal, fossorial snakes, so are infrequently seen by people. The Palaeocastorinae include beavers that are interpreted as fossorial (burrowing), as are nothodipoidins and "Migmacastor". Gopherus is a genus of fossorial tortoises commonly referred to as gopher tortoises.