How squid beaks work

CBC reports on a conundrum resolved:

Squids use their sharp beaks, one of the hardest materials found in nature, to slice through the spinal cords of their prey, fish, and defend themselves against sperm whales, their main predator other than humans.

The beaks attach to the soft tissue inside the squid's mouth and as such has made researchers question why the squids don't get cut every time they attack a fish.

"Here you have a 'cutting tool' that's extremely hard and stiff at its tip and is attached to a material — the muscular buccal mass [the soft tissue of the squid's mouth] — that has the consistency of Jell-O," said study co-author Frank Zok, a professor at the university's Department of Materials, in a release. . . .

To solve the mystery, the research team painstaking studied the chemical composition of the sharp beak of the Humboldt squid. They found that the components in the beak — polysaccaride chitin, water and protein enriched in the compound Dopa and amino acid histidine — slightly change in quantities between the tip and the base. Dopa is concentrated at the tip, and gradually decreases as it moves toward the beak, the researchers found.

When mixed with water, the beak becomes increasingly soft and bendable as it moves toward the mouth. However, when the base dries out, it becomes as stiff as the tip.

"Nature takes care of the problem by changing the beak composition progressively, rather than abruptly, so that its tip can pierce prey without harming the squid in the process," Zok said. "It's a truly fascinating design!"

The article suggests that nails and glue could eventually become things of the past.

Photo of squid beak from Science magazine.