Narwhals seem like magical creatures, the unicorns of the sea. Unfortunately, in real life, there is no magic, but there’s still an air of wonder about them, thanks in large part to their huge, majestic horn—which is really just a very long tooth, one that scientists have recently discovered is actually made up of two spirals twisting in opposite directions to help keep it straight as it grows.
The study, published in Nature Communications, used a combo of X-ray imaging techniques to examine two male narwhal tusks down to their microscopic structure. Researchers found that while the outer cementum twists to the left, the inner dentine twists the other way.
Narwhal tusks can grow nearly seven feet long and are actually canine teeth that pop out through the whale’s upper lip. They’re most common in males and are believed to have evolved mostly through sexual selection, essentially functioning as a long, pointy, and rather on-the-nose symbol of virility. Their exact purpose, though, is up for debate, since narwhals have been known to use them to stun fish, and millions of nerve endings in them allow the creature to detect changes in surrounding water. It’s a multipurpose horn that is just as practical as it is decorative.
Narwhal Tusks Are Multipurpose Marvels
The opposing spirals solve the very practical problem of ensuring the horn doesn’t bend, twist, or curl as it grows. Those inner and outer tissues twisting against one another create an internal tension the tusk straight while maintaining flexibility and resistance to cracking. That’s its biological purpose. It also serves a scientific purpose for human researchers. The horn keeps growing throughout the narwhal’s entire life; all the while, its hard tissue preserves a record of the changing environmental conditions in the Arctic that researchers can later study.
No, it’s not a magical task, but it is a self-straightening organic environmental time capsule that’s poking out of the whale’s face, which is actually much cooler.
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