The crab belongs to the soft armor, decapod, is a crustacean, the body is protected by a hard shell, relying on gills to breathe. In biological taxonomy, it and shrimp, lobster, hermit crabs are the same kind of animal. The vast majority of species of crabs live in the sea or offshore areas, with some inhabiting freshwater or land. Common crabs include pike crabs, distant sea pike crabs, green crabs and Chinese mitten crabs (river crabs, hair crabs, clear water crabs).