Narwhals, the mysterious arctic whales with a long horn like a unicorn, are in the news again as several people were recently charged with smuggling narwhal horns, which may be worth $30,000 or more apiece. Now, although that’d be a lot to find under your pillow after a visit from the tooth fairy, there’s a lot more value to these horns than the cash they command on the open market.

For example, the narwhal tusk is unique in all the world. Not only is it the only straight tusk, it’s also the only tooth that seems designed for sensitivity.

What Is the Narwhal Tusk?

The narwhal tusk is actually a tooth from the upper jaw that instead of growing downward grows forward through the skull. The tusk we see is almost always on the left side. The right tooth also grows forward, but usually isn’t long enough to be visible. The tusk grows in a spiral, unlike any other tooth known.

The uniqueness of the narwhal tusk has led researchers to wonder what is the purpose of this miraculous tooth.

Narwhals Are Underwater Peacocks (or Rams)

Since by and large only male narwhal have tusks, the primary function of the narwhal tusk is probably for display, like the peacock’s tail, or dominance battles, like a ram’s horns. Which is more important hasn’t been deciphered yet, because we still know very little about these creatures.

With the tusk growing to be more than a third of the male whale’s total length, it’s likely that size is an important selection factor, but whether that’s for display or for battles, we don’t know.

Narwhal battles aren’t like jousting competitions. They’re more like closely-fought sword duels. The males press their heads together and rub their horns against each other until one seemingly relents.

Sensitive Males

However, although the sexual selection argument still holds a great deal of sway because the tusk is overwhelmingly a male feature, recent research suggests that narwhal teeth have a secondary function: they’re designed to sense water conditions.

Unlike most teeth, the narwhal tusk has its enamel underneath, surrounding the pulp. On the outside is a more porous, dentin-like material, and through this material threads millions of nerve endings. These nerves allow the narwhal to sense changes in the water, everything from temperature changes to pressure changes to the chemicals given off by the fish they eat. This gives the narwhal an important tool for sensing its environment and utilizing the resources.

Although it’s useful, it can’t be that useful, or else females would likely also have them as well. And, who knows, maybe they will. Sometimes females have tusks, and if they prove useful for purposes other than mating and display, it’s like that more and more females will have them in time.

So although for you, tooth sensitivity may send you running to the dentist, for the narwhal it gives them new ways to sense their environment, like a snake’s tongue or an ant’s antennae. And it’s really the males who are the most sensitive members of the narwhal family.