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American Association for the Advancement of Science

Mystery of the squid beak solved

Beak of the Humboldt squid Dosidicus gigas.

A squid's mouth has a sharp beak that it uses to slice through the spinal cord of fish and tear them into pieces for an easy-to-eat meal. The squid beak is made out of some of the hardest material found in nature. Squid beaks have even been discovered inside the stomachs of whales, because they were just too tough for the whales to digest.

But there's a problem with the squid beak, and it goes like this. What if you had the best knife around, but it didn't have a handle? You could cut through anything you wanted, but such a sharp blade would also slice up your hands every time you used it. The squid beak is hard and sharp, but it doesn't have a hard and sharp handle. Instead, it attaches to the soft tissue inside the squid's mouth.

So why doesn't that tissue get cut up each time the squid attacks a fish? According to Ali Miserez of the University of California, Santa Barbara and his fellow researchers, the beak is made of slightly different materials at its "knife" and "handle" end. A certain mix of proteins and water makes the knife end hard and stiff. And a slightly different mix of these ingredients makes the beak grow softer and more bendable at the place where it attaches to the mouth. The softer handle end keeps the squid from cutting itself when it uses its beak.

More details about the squid's amazing beak appear in the 28 March 2008 issue of the journal Science.