Ice unicorn
The narwhal (Monodon monoceros) is a whale ranging in size from 3.8-5m (12.5-16.4 ft; excluding the tusk), and which can weight up to 1,600kg (3,528 lbs.). Along with the beluga (Delphinapterus leucas), the narwhal belongs to the Monodontidae family. Both of these species are in the odontocetes suborder, which regroups the dolphins, the porpoises and the toothed whales. In fact, what we refer as the narwhal tusk is a tooth. Although it is generally only males that bear a tusk, some females were seen with a tooth protruding from their skull. Generally, only one tooth erupts, and it can measure up to 3m (9.84 ft). However, two erupted teeth have been seen on some narwhals. A variety of functions have been suggested for the tusk, such as feeding or sound transmission, but none has been confirmed. One of the hypotheses for its function is that the tusk serves in male-male displays and fighting. This is similar to other sexually dimorphic organs, such as horns and antlers, which serves in competitions for female access.

Narwhals have a varied diet, which include fish such as the Arctic cod (Boreogadus saida), the Greenland halibut (Reinhardtius hippoglossoides), and the polar cod (Arctogadus glacialis), as well as a species of deep-sea squid (Gonatus fabricii) and crustaceans (Pasiphaea tarda, Hymenodora glacialis, Boreomysis nobilis).

The narwhal is the northernmost distributed whale. It is mainly found in the Canadian Arctic and in Greenland waters. For hunt-management purposes, the Department of Fisheries and Oceans (DFO) of Canada identified three populations, two of which, the Baffin Bay and the Hudson Bay populations, inhabit the Canadian waters. As some narwhal groups have been reported in Iceland, Norway (Svalbard), the United States (Alaska), and in Russia, there is likely other of small size populations. Unfortunately, the habitat of the narwhals has been receiving greater attention recently, as it is stressed by climate change and by the imminent opening of the Northwest Passage.

Most Canadian narwhals winter in the heavy pack-ice of the Davis Strait, migrate North during the spring to reach their summering areas, the fjords and inlets in Baffin and Somerset Islands, as well as in northwest Greenland. During the fall, the whales generally use the reverse paths to go back to their wintering area. The population of the Hudson Bay moves between their wintering area, the mouth of the Hudson strait, and their summering area, waters surrounding Southampton Island.

Man and narwhals
The narwhal, with its distinctive tusk, is at the origin of the unicorn myth. Following the return of Vikings to Scandinavia during the 11th century, a high-end market developed in Europe for powdered tusk. Today the tusk is especially prized in the global ivory market, in which a two-tusked skull can be worth as much as $90,000. Although the tusk is the valuable part of the narwhal in the exportation market, the Inuit of Greenland and of Canada regard the narwhal's skin and adhering blubber, known as maqtaq, as one of their favourite traditional food.

There are disagreements between scientists and organizations regarding the population estimates for narwhals. Further, the World Conservation Union (IUCN) considers the narwhal as 'data deficient' and the species was newly placed under the 'special concern' status by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Many other factors are threatening the narwhals. The climate changes are likely to affect the ice conditions which in turn will probably disturb the narwhals' distribution and survival. Further, the mining corporation Baffinland is planning to open of an iron ore mine on Baffin Island, near Pond Inlet. The construction and operation of such a mine involve the use of barges and ice breakers in the Eclipse Sound's region where the narwhals gather during the summers for calving.

Source: http://whitelab.biology.dal.ca/mm/narwhal.html