A wyvern (pronounced "why vern"), sometimes spelled wivern, is a legendary winged creature with a dragon's head (which may be said to breathe fire or possess a venomous bite) and wings; a reptilian body; two legs (sometimes none); and a barbed tail. A sea-dwelling variant, dubbed the sea-wyvern, has a fish tail in place of a barbed dragon's tail. The wyvern in its various forms is important to heraldry, frequently appears as a mascot of schools and athletic teams (chiefly in the United States and United Kingdom), and occasionally appears in medieval and modern European and British literature as well as a multitude of video games. It is often mistaken for a dragon, which has four legs and a pair of wings, as opposed to a wyvern, which has no more than two legs and a pair of wings. it is often considered a subspecies of dragon.