Musk deer can refer to any one of, or all seven species, that make up Moschus, the only extant genus of the family Moschidae. Musk deer are more primitive than cervids, or true deer, because they lack antlers and facial glands, and possess only a single pair of teats, a gall bladder, a caudal gland, a pair of tusk-like teeth and—of particular economic importance to humans—a musk gland.
Musk deer live mainly in forested and alpine scrub habitats in the mountains of southern Asia, notably the Himalayas. Moschids, the proper term when referring to this type of deer rather than one/multiple species of musk deer, are entirely Asian in their present distribution, being extinct in Europe where the earliest musk deer are known to have existed from Oligocene deposits.
Musk deer resemble small deer with a stocky build, and hind legs longer than their front legs. They are approximately 80 to 100 centimetres (31 to 39 in) long, 50 to 70 centimetres (20 to 28 in) tall at the shoulder, and weigh between 7 and 17 kilograms (15 and 37 lb). The feet of musk deer are adapted for climbing in rough terrain. Like the Chinese water deer, a cervid, they have no antlers, but the males do have enlarged upper canines, forming sabre-like tusks. The dental formula is similar to that of true deer: 0.1.3.33.1.3.3
The musk gland is found only in adult males. It lies in a sac located between the genitals and the umbilicus, and its secretions are most likely used to attract mates.
Musk deer are herbivores, living in hilly, forested environments, generally far from human habitation. Like true deer, they eat mainly leaves, flowers, and grasses, with some mosses and lichens. They are solitary animals, and maintain well-defined territories, which they scent mark with their caudal glands. Musk deer are generally shy, and either nocturnal, or crepuscular.
Males leave their territories during the rutting season, and compete for mates, using their tusks as weapons. Female musk deer give birth to a single fawn after about 150–180 days. The newborn young are very small, and essentially motionless for the first month of their life, a feature that helps them remain hidden from predators.
It is rumored that ancient royalty wore the scent of the musk deer and that it is an aphrodisiac.