Puzzle 22

John Baez

Q: Which animal has a tusk 2 to 3 meters long that grows through its upper lip?

A: A male narwhal. The narwhal, Monodon monoceros, is an unsual sort of Arctic whale, bluish-gray with white blotches. The females weight 1 ton at maturity, and the males 1.6 tons.

Narwhals have two teeth in their upper jaw, but the male's left tooth grows through its upper lip and becomes a a "horn" or "tusk" 2 to 3 meters long. The base of the tusk is usually infested with lice. Nobody knows what his tusk is for - perhaps it's a jousting weapon used in courtship battles? Narwhal tusks were once thought to come from unicorns.

Narwhals eat fish, squid, shrimp, and other marine life. They stay near ice and live in groups called "pods" and communicate by a system of squeals, trills, whistles and clicks. Sometimes many pods travel together. The Inuit (or "Eskimos") hunt narwhals.

Barry Lopez writes:

Narwhals live in close association with ice margins and are sometimes found far inside havey pack ice, miles from open water. How they determine whether the lead systems into the ice will stay open behind them, ensuring their safe return, is not known. They manage to survive in areas of strong currents and wind where the movement of ice on the surface is violent and where leads open and close, or freeze over, very quickly. Like seabirds, they seem to have an uncanny sense of when a particular lead is going to close in on them, and they leave. That they are not infallible in anticipating the movement and formation of ice, which seals them off from the open air and oxygen, is attested to by a relatively unusual and often fatal event called a savssat.

Savssats are most commonly observed on the west coast of Greenland. Late in the fall, while narwhals are still feeding deep in a coastal fiord, a band of ice may form in calm water across the fiord's mouth. The ice sheet may then expand toward the head of the fiord. At some point the distance from its landward to its seaward edge exceeds the distance a narwhal can travel on a single breath. By this time, too shorefast ice may have formed at the head of the fiord, and it may grow out out to meet the ice sea. The narwhals are thus crowded into a smaller and smaller patch of open water. Their bellowing and gurgling, their bovinelike moans and the plosive screech of their breathing, can sometimes be heard at a great distance.

Source: Barry Lopez, Arctic Dreams, Bantam Press, 1988. For more information about narwhals - and pictures! - try:

Recently scientists have discovered that the narwhal's tusk has nerves:

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