| The narwhal's tusk is a tooth - an upper-jaw tooth that grows through the lip and keeps on growing. Narwhals have just two teeth, both in the upper jaw. Usually the right tooth remains small and the left one grows to become the tusk. It can weigh more than 10 kg and grow to 3 m long; an average-size male narwhal, not counting the tusk, is 4.76 m long. Very rarely, males grow two tusks, and now and then a female develops a tusk. Tusks probably play a role in breeding competition. Narwhals migrate, wintering in pack ice and summering in deep sounds and fjords. They make deep dives - satellite transmitters are beginning to provide information on their diving habits - and feed near the bottom, probably capturing their prey by suction and swallowing it whole. Killer whales and polar bears are predators, and humans hunt them for their skin, meat, and ivory tusks.
Males are larger than females.
4.7 m males; 4.1 m females
1,580 kg males; 960 kg females
Linnaeus, C., 1758. Systema Naturae per regna tria naturae, secundum classis, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Tenth Edition, Laurentii Salvii, Stockholm, 1:75, 824 pp.
Mammal Species of the World
Click here for The American Society of Mammalogists species account
Click to enlarge.