Beluga and Narwhal: Monodontidae

Physical characteristics: Narwhals grow to be about 14 to 15.5 feet (4.2 to 4.7 meters) long and weigh 2,200 to 3,500 pounds (1,000 to 1,600 kilograms). Males are much larger than females.

The most outstanding physical feature of the narwhal is its ivory tusk. The tusk is a tooth that in males grows out of the left side of the upper jaw in a counter-clockwise spiral. Tusks can grow to be one-third the length of the body, or 30 feet (10 meters) long, and weigh 20 pounds (10.5 kilograms). Narwhals have two teeth in the upper jaw, and occasionally the right tooth will also grow into a tusk. Once in a great while, a female will develop a tusk. Tusks are often broken, but will heal and continue to grow.

Geographic range: Narwhals are limited to the coldest Arctic waters. They are not evenly distributed and are rare along Alaska, Siberia, and parts of Arctic western Canada.

Habitat: Narwhals live in colder water than any other whale. They follow the ice pack, moving north in the summer as it retreats and south in the winter as it grows. They often swim long distances under thick ice, coming up to breathe in small cracks called leads.

Diet: Narwhals feed along the sea bottom, eating squid and deep water fishes. They can dive to depths of about 3,300 feet (1,000 meters) and stay under water for up to twenty-five minutes. They locate their food by echolocation. Echolocation involves making sounds that bounce off objects. Sense organs pick up the echo or reflected sound and use information about its the timing, direction, and strength to determine the location of objects.

Behavior and reproduction: Narwhals are social animals. They live in groups or pods of three to eight individuals, usually of the same sex and age. When they migrate, these pods may gather to form groups of hundreds or even thousands of animals. Narwhals have been known to work cooperatively to open breathing holes in the ice. Several animals will simultaneously butt their foreheads against the ice sheet in order to break it. This suggests that they have some form of group communication.

Narwhals mate in the early spring and have a single calf in July or August of the following year. Scientists are not sure, but they think that males fight each other with their tusks for the right to mate. Females normally produce a calf every three years. Pregnancy lasts about fifteen months. Newborns are 5 feet (1.6 meters) long and weight about 175 pounds (80 kilograms). They are born with a 1-inch (2.5-centimeter) thick layer of blubber to protect them from the cold water. Calves nurse for about twenty months and may remain with their mother longer. They become physically mature between four and seven years of age and can live fifty years in the wild. Natural predators of the narwhal are the killer whale and the Greenland shark.

Narwhals and people: The ivory in the tusks of narwhals has commercial value. It is often carved into jewelry or decorations. The tusks are also sold as curiosities to collectors. In earlier times, narwhal tusks brought back by sailors may have given rise to the story of the unicorn, a one-horned horse.

Conservation status: Not enough is known about the population of narwhals to give them a conservation ranking. Threats include being hunted for food and for their tusks. Global warming is of particular concern to the survival of this species, because they live in and around the ice pack. ∎