Otters

Otters are small to medium-sized mammals with a long body, flattened head, broad muzzle, and long stiff whiskers. Their tail is strong, long, flattened, and somewhat tapered. Otters have short legs and webbed toes; they are well adapted to a semi-aquatic existence and are skilled swimmers. The outer fur of otters is short, very dense, and highly water resistant. They also have a layer of soft underfur that traps an insulating layer of air and helps them stay warm when in the water. Otters are carnivores and have teeth adapted either to eating fish or to crushing the shells of crustaceans, depending on the diet of the species. The ears of otters are small and can close when swimming (with the help of special muscles), while their hearing is good. Their eyes are small but their sight is good due to special lenses that help them see clearly underwater. Male otters are about 28% larger than females.

Otters are members of the weasel family, Mustelidae. There are five subfamilies within this family: weasels, minks, and polecats (Mustelinae); skunks (Mephitinae); badgers (Melinae); honey badgers (Mellivorinae); and otters (Lutrinae). The Lutrinae subfamily includes six genera: sea otters, river otters, clawless otters, giant otters, and two genera of small-clawed otters. There are 18 species, with about 63 subspecies (depending on the taxonomic treatment).