Knowledge in a squid’s beak

The razor-sharp beaks that giant squids use to attack might one day lead to improved artificial limbs for people.

That deadly beak has long puzzled scientists, who wondered how a creature without any bones could wield it without hurting itself.

Researchers at UC Santa Barbara reported Friday in the journal Science that they have an explanation.

The beak, made of hard chitin and other materials, changes density gradually from the hard tip to a softer, more flexible base where it attaches to the muscle around the squid’s mouth, they found.

That means the tough beak can chomp away at fish for dinner, but the hard material doesn’t press or rub directly against the squid’s softer tissues.

Molecular biologist Herbert Waite, a co-author of the paper, said such graduated materials could have broad applications in biomedical materials.

“Lots of useful information could come out of this for implant materials, for example. Interfaces between soft and hard materials occur everywhere,” he said in a telephone interview.

Waite and his colleagues calculated the changes in the squid beak by carefully measuring the ratios of chitin (the material in, for example, insect shells) and water and proteins in the beaks of Humboldt squid, showing gradual changes from tip to base.

Waite said it was the first time this had been calculated. He said he was surprised that the main difference in density resulted from the amount of water included in each part of the beak.