According to the University of Michigan's Department of Zoology, the family Mustelidae includes 56 species of weasels, otters, badgers and their relatives. Most members of the family have elongated bodies, short legs and compact heads, but badgers and wolverines have broader builds. Mustelids have very strong jaws and sharp canine teeth they use to kill their prey.
The smallest mustelid species is the least weasel. Least weasels are only about six inches long and rarely exceed one-half pound in weight. By contrast, wolverines reach 70 pounds in weight, while sea otters occasionally reach 100 pounds. All are primarily carnivorous, but some species may eat plant matter from time to time. Large mustelids often hunt and consume the smaller members of the group. Mustelids serve important roles in the ecosystems in which they live and help to regulate rodent and bird populations.
Mustelids live on every continent except Antarctica and Australia. Most forms are terrestrial, but a few, including the otters, minks, martens and fishers, are almost fully aquatic. Some mustelids, such as fishers and martens, are accomplished climbers, while others, such as badgers and wolverines, are capable excavators.
While skunks were formerly considered relatives of the mustelids, molecular evidence has recently been used to move them into the family Mephitidae.