You’ve probably heard of the narwal. It’s a whale with a huge tusk coming from its forehead, and the tusks were sold in the middle ages around the world as unicorn horns.

Males weigh up to 1.5 tons, grow about 15 feet long and are conspicuous by their tusks, which can grow from six to nine feet in length. A few females have tusks and, in rare cases, narwhals can wield two of the long teeth. Though often ramrod strait, the tusks always grow in tight spirals that, from the animal’s point of view, turn counterclockwise.

The horn has presented a problem for scientists for a long time now, because they really didn’t know what they are for. They occur in the males and sometimes in females, they aren’t used for fighting according to Inuit witnesses, and there seems to be few good practical applications for them, but in a paper being presented today it has been discovered that the horn has masses of nerve endings going along it, exposed to the environment directly through tiny tubules. This is really puzzling, because the horn is just an oddly placed and shaped tooth, and we get tooth ache when our teeth decay, exposing the nerve endings to the cold. For some reason, narwals living in freezing waters have evolved exposed nerve endings but no-one’s quite sure why. Possibly it’s to help them measure the weather, or to detect changes in the water that suggest when it will freeze over (like other whales, they need to surface to breath, so getting trapped under the ice is a major hazard for them).

Of course, there’s another, more amusing, option:

Dr. Nweeia noted that the discovery does not eliminate some early theories of the whale’s behavior. Tusks acting as sophisticated sensors, he said, may still play a role in mating rituals or determining male hierarchies.

He added that the nerve endings, in addition to other readings, undoubtedly produce tactile sensations when the tusk is rubbed or touched, and that these might be interpreted as pleasurable.

This tactile sense might explain why narwhals engage in what is known as “tusking,” where two males gently rub tusks together, Dr. Nweeia said.

Gay whales! Hurrah! No wonder some of the females grow them as well, although maybe they then become lesbians? Perhaps the whole narwal community is involved is massive bisexual teeth-rubbing orgies! You didn’t see that in March of the Penguins did you?

On a slightly more serious note, there’s some interesting stuff about the history of unicorns on the second page of the article, including this snippet:

Churches put small pieces of “unicorn horn” in holy water, giving ailing commoners hope of miracle cures.

I’ve always liked narwals, primarily because of the unicorn-hoax association I think, but they’re a strange looking creature and such things always capture the imagination (like the duck-billed platypus). It’s an interesting article that gets more interesting as it goes on, you can read here.