Otters are amphibious (or in one case aquatic) fish-eating mammals. The otter subfamily Lutrinae forms part of the family Mustelidae, which also includes weasels, polecats, badgers, as well as others. With thirteen species in seven genera, otters have an almost worldwide distribution.They eat mainly fish, clams, lobsters, shrimp, and mice if they have to. Otters are playful animals, for example sliding repeatedly down snowy slopes, apparently from sheer enjoyment.