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MUSTELIDAE - badgers, otters, weasels, and relatives
This family, containing approximately 65 species, is the largest in Carnivora, being twice as large as the next largest family, the Herpestids. They are found on all continents except Australia and Antarctica. They are also not found on most oceanic islands, such as Madagascar, most of the Philippines, the West Indies, New Zealand, and New Guinea. Members of this family include weasels, stoats, polecats, mink, marten, fishers, wolverines, otters, badgers and others. While many authors have traditionally considered skunks a subfamily within , recent molecular evidence indicates that skunks do not lie within the mustelid group and instead are recognized as a single family, Mephitidae.
Mustelids inhabit all continents except Australia and Antarctica, and do not occur on Madagascar or oceanic islands. Members of this group can be found in diverse habitats, which include both terrestrial, aquatic and marine environments. Mustelids are mainly carnivorous, with various members of the family exploiting a great diversity of both vertebrate and invertebrate prey. Mustelids are generally proficient hunters; some weasels can take prey larger than themselves. Members of this family often hunt in burrows and crevices, and some species have evolved to become adept at climbing trees (e.g., marten) or swimming (e.g., sea otters, mink) in search of prey. (Nowak, 1991; Sato et al., 2003; Vaughan, Ryan, and Czaplewski, 2000; Whitaker and Hamilton, 1998)
Generally, mustelids have elongate bodies with short legs and a short rostrum, as typified by weasels, ferrets, mink, and otters. Wolverines and badgers have broader bodies. An order of magnitude difference in size exists between the smallest and largest mustelid species. The smallest species is the least weasel (Mustela nivalis), weighing between 35 and 250 grams. Wolverines (Gulo gulo) and sea otters (Enhydra lutris) reach 32 kg and 45 kg, respectively. All mustelids have well developed anal scent glands, which serve various functions, including territorial marking and defense.
The morphological characters considered to unite all mustelids are enlarged anal scent glands, the loss of the second upper molar, and the loss of the carnassial notch on the fourth upper premolar. Mustelids share these characters with skunks, the main reason for their historical inclusion in the family. These characters may be the result of convergent evolution, however. For example, all carnivores have enlarged scent glands, and those of skunks are much more enlarged than in . Furthermore, the anal scent gland in skunks is associated with a nipple, rather than a duct as in .
The mustelids are generally small to medium sized animals. They
range in size from the least weasel, weighing 35-70 g (1-2 oz.)
to the giant otter, which can weigh up to 35-40 kg (77-88 lb.).
Male mustelids are usually about 1/4 larger than females. They
generally have a slender, long body structure set on short legs.
Their tails are generally long. They have short, rounded ears
set low on their heads. All mustelids have highly-developed anal
glands, which are defensive weapons in such species as the