This family of 23 Recent genera and 65 species occurs in all land areas of the world except the West Indies, Madagascar, Sulawesi and islands to the east, most of the Philippines, New Guinea, Australia, New Zealand, Antarctica, and most oceanic islands. One genus, Enhydra, inhabits coastal waters of the North Pacific. The largest members are the otters Pteronura and Enhydra, which have a head and body length of around 1 meter or more and a weight of 22-45 kg.
Male mustelids are about one-fourth larger than females.
The pelage is either uniformly colored, spotted, or striped. Some species of Mustela turn white in winter in the northern parts of their range. The short ears are either rounded or pointed. The limbs are short and bear five digits each. The claws are compressed, curved, and nonretractile.