The narwhal (Monodon monoceros), also known as a narwhale, is a medium-sized toothed whale that lives year-round in the Artic. One of two living species of whale in the Monodontidae family, along with the beluga whale, narwhal males are distinguished by a long, straight,helical tusk, actually an elongated upper left canine. Found primarily in Canadian Artic and Greenlandic waters, rarely south of 65°N latitude, the narwhal is a uniquely specialized Arctic predator. In the winter, it feeds on benthic prey, mostly flatfish, at depths of up to 1500 m under dense pack ice. Narwhals have been harvested for over a thousand years by Inuit people in northern Canada and Greenland for meat and ivory, and a regulated subsistence hunt continues to this day. While populations appear stable, the narwhal is particularly vulnerable to climate change due to a narrow geographical range and specialized diet.
Narwhals are medium-sized whales, and equivilent to the size of beluga whales. Total length in both sexes, excluding the tusk of the male, can range from 3.95 to 5.5 m (13 to 18 ft). Males are slightly larger than females, at an average length of 4.1 m (13 ft 5 in), , with an average length of 3.5 m (11 ft 6 in). Typical adult body weight ranges from 800 to 1,600 kg (1,800 to 3,500 lb). Male narwhals attain sexual maturity at 11 to 13 years of age, when they are about 3.9 m (12 ft 10 in) long. Females become sexually mature at a younger age, between 5 to 8 years old, when they are around 3.4 m (11 ft 2 in) long.
The pigmentation of narwhals is a mottled pattern, with blackish-brown markings over a white background. They are darkest when born and become whiter with age; white patches develop on the navel and genital slit at sexual maturity. Their neck vertebrae are jointed, like those of land mammals, instead of being fused together as in most whales. Both these characteristics are shared by the beluga whale. The tail flukes of female narwhals have front edges that are swept back, and those of males have front edges that are more concave and lack a sweep-back. This is thought to be an adaptation for reducing drag caused by the tusk.