Marine Wildlife Encyclopedia
Narwhal Monodon monoceros
The male narwhal is instantly recognizable by its unicorn-like tusk, which is up to 10 ft (3 m) long. A highly modified upper tooth, the tusk emerges through the narwhal’s upper lip, developing spiral grooves as it grows.
Apart from this outstanding feature, males and females are similar, with a long cylindrical body, a bulbous head, and very short, beaklike jaws.
Narwhals are dappled gray above and pale or white beneath. The function of the narwhal’s tusk is unclear. It may be used for ritual combat during the breeding season, or even as a navigational aid, as it is packed with nerves.