Narwhal tusks: Delicate sensing organs?

For centuries, people have made up weird explanations for why the 1.5-ton narwhal has a long, spiralled tusk. Sailors claimed the beasts wielded them in battle; Jules Verne wrote that a narwhal tusk could slice open a ship’s hull “as easily as a drill pierces a barrel.” Later, snake-oil merchants passed them off as unicorn horns, or ground them up and sold the powder as a cure for everything from impotence to scurvy. But the actual function of the tusk remained a mystery …

… until now. A bunch of scientists from Harvard and the National Institute of Standards and Technology carefully studied a tusk in a lab and, as the New York Times today reports, got a shock:

The find came when the team turned an electron microscope on the tusk’s material and found new subtleties of dental anatomy. The close-ups showed that 10 million nerve endings tunnel from the tusk’s core toward its outer surface, communicating with the outside world. The scientists say the nerves can detect subtle changes of temperature, pressure, particle gradients and probably much else, giving the animal unique insights.

“This whale is intent on understanding its environment,” said Martin T. Nweeia, the team’s leader and a clinical instructor at the Harvard School of Dental Medicine. Contrary to common views, he said, “The tusk is not about guys duking it out with sticks and swords.”

That’s just awesome. Apparently this violates all known tooth anatomy (a sentence I did not really ever anticipate writing). Tubules in normal teeth never go to the surface. Apparently a team of Canadian scientists recently captured a live narwhal, put sensors on its head, and discovered that its brain-wave activity changes as the salinity in the water changes — which supports the idea that the tooth is a sensing device.

There really is not enough mainstream coverage of narwhal science, if you ask me.

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I'm Clive Thompson, the author of Smarter Than You Think: How Technology is Changing Our Minds for the Better (Penguin Press). You can order the book now at Amazon, Barnes and Noble, Powells, Indiebound, or through your local bookstore! I'm also a contributing writer for the New York Times Magazine and a columnist for Wired magazine. Email is here or ping me via the antiquated form of AOL IM (pomeranian99).

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