Squid beaks and materials science

Clive Thompson's got a fascinating rumination on what a revelation about the composition of the Humboldt squid's razor-sharp beak means for materials science:

There are many weird things about the giant Humboldt squid, but here's one of the strangest: Its beak. The squid's beak is one of the hardest organic substances in existence – such that the sharp point can slice through a fish or whale like a Ginsu knife. Yet the beak is attached to squid flesh that itself is the texture of jello. How precisely does a gelatinous animal safely wield such a razor-sharp weapon? Why doesn't it just sort of, y'know, rip off? It's as if you tried to carve a roast with a knife that doesn't have a handle: It would cut into your fingers as much as the roast.

This question has haunted many a marine biologist. So recently a team of materials scientists at the University of California decided to carefully examine the physical properties of the beak. Their discovery? The beak contains a huge gradation of stiffness: The tip of the beak is 100 times more rigid than the base of the beak – so the base can blend easily with the surrounding flesh. Water is the key to the proper functioning of this gradient: If the beak is dried out, the soft base calcifies until it's nearly as dense and rigid as the peak. (You can read their paper – "The Transition from Stiff to Compliant Materials in Squid Beaks" in PDF format here.)

Now the scientists are trying to figure out how to artificially replicate this remarkable gradient, because it's so radically different from the way we humans traditionally develop materials. We know how to create materials that are really stiff or really soft, but not ones that slide gradually from one to the other extreme.

The Humboldt squid beak: Diamond-sharp mystery of the briny deep