Mustelidae
The Mustelidae (/mʌˈstɛlɪdiː/;[2] from Latin mustela, weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids (/ˈmʌstɪlɪdz/[3]) are a diverse group and form the largest family in the order Carnivora, suborder Caniformia. They comprise about 66–70 species across nine subfamilies.[4]
Mustelids vary greatly in size and behaviour. The least weasel can be under a foot in length, while the giant otter of Amazonian South America can measure up to 1.7 m (5 ft 7 in) and sea otters can exceed 45 kg (99 lb) in weight. Wolverines can crush bones as thick as the femur of a moose to get at the marrow, and have been seen attempting to drive bears away from their kills. The sea otter uses rocks to break open shellfish to eat. Martens are largely arboreal, while European badgers dig extensive tunnel networks, called setts. Some mustelids have been domesticated; the ferret and the tayra are kept as pets (although the tayra requires a Dangerous Wild Animals licence in the UK), or as working animals for hunting or vermin control. Others have been important in the fur trade—the mink is often raised for its fur.
Being one of the most species-rich families in the order Carnivora, the family Mustelidae also is one of the oldest. Mustelid-like forms first appeared about 40 million years ago (Mya), roughly coinciding with the appearance of rodents. The common ancestor of modern mustelids appeared about 18 Mya.[4]
Within a large range of variation, the mustelids exhibit some common characteristics. They are typically small animals with elongated bodies, short legs, short, round ears, and thick fur.[5] Most mustelids are solitary, nocturnal animals, and are active year-round.[6]
With the exception of the sea otter,[7] they have anal scent glands that produce a strong-smelling secretion the animals use for sexual signaling and marking territory.
Most mustelid reproduction involves embryonic diapause.[8] The embryo does not immediately implant in the uterus, but remains dormant for some time. No development takes place as long as the embryo remains unattached to the uterine lining. As a result, the normal gestation period is extended, sometimes up to a year. This allows the young to be born under favorable environmental conditions. Reproduction has a large energy cost, so it is to a female's benefit to have available food and mild weather. The young are more likely to survive if birth occurs after previous offspring have been weaned.
