(HOST) Commentator Ruth Page has discovered the relationship between unicorns and creatures known as narwhals.

(PAGE) Once, in England, I watched a woman creating a new tapestry from a beautiful old pattern that included a unicorn. Her work was meticulous. As I saw her try to reproduce the unicorn's horn, one minute thread at a time, she was giving it a noticeable leftward twist. I'd seen this in storybook pictures of the fabulous creatures, too, and wondered: why the twist?

Two years later, I've found out, in reading about narwhals. I've never seen them anywhere but in photographs; they don't survive well in captivity. Narwhals are medium-sized whales, their world population estimated at some fifty thousand. They're among the world's deepest-diving mammals; in the depths, in winter, they feast on halibut. Like so many other preposterous-looking ocean creatures, many are dying from pollution. Study of narwhals has been heating up for several years, and a few of the creatures have been tagged so their travels can be studied.

Narwhals are gentle creatures, despite that long "horn" that looks sharp and dangerous. The "horn" is a stunningly long tooth that stretches as much as half the length of the animal's whole body. The tusk curves gracefully to the left, the only tooth on the planet known to do so. And it is a tooth, though its protective enamel is on the inside. The outer covering is much softer and more vulnerable. A group of dentists currently studying the animals points out that a few hundred years ago, if you ordered a "unicorn horn," what you received was a two-to-three-meter long narwhal tooth; and that's why unicorn horns curve to the left.

Because the outer layer of the narwhal tooth is now known to be soft, early speculation about how the tooth is used was 'way off base. A narwhal can't spear prey with it, can't fight with it, can't dig with it. It's much too tender. When two males meet, they don't fight with the teeth; their heads just sway from side to side. The tusks touch but never clash.

Harvard dentist Martin Nweeia, whose dental office is in Connecticut, became so curious he traveled to the Canadian Arctic for four field seasons to study the animals. It wasn't easy. Narwhals spend their lives within the Arctic Circle. For six months of winter, the animals stay in offshore icefields where even the Inuit rarely try to reach them. The cold was bitter, Nweeia reported, even during the other seasons.

Nweeia worked with associates to try to figure out why such "unicorn horns" ever evolved. They concluded that they're (quote) "exquisitely sensitive." Perhaps they sense not only pressure and temperature but maybe even water chemistry, to help the animal find food sources or mates. No one has ever seen a mating, or watched a female narwhal give birth, so there is still much to be learned.

Ruth Page has been following environmental issues for twenty years. She is a long time Vermont resident and currently lives in Shelburne.