Researchers in the US have finally worked out how the aggressive and slightly-scary Humboldt squid avoids turning itself into calamari when eating.
Because it has a pretty squidgy body and a very hard beak, you might expect the squid to do just as much damage to itself as its prey when chomping down on a passing fish or scuba diver.
“You can imagine the problems you’d encounter if you attached a knife blade to a block of Jell-o and tried to use that blade for cutting,” says Frank Zok, author of a new paper on squid beaks in Science (press release, paper). “The blade would cut through the Jell-o at least as much as the targeted object.”
Obviously this doesn’t happen with the Humboldt, or the animals wouldn’t be swarming like roaches across our seas. In fact the squids have a neat trick – a graduated tissue where the base of the beak is 100 times softer than the tip.
The team mapped the composition of sections of the squid’s beak. Its properties are determined by the ratio of chitin, water and proteins. Changes in the ratio of these change the beak’s properties.
“I’d always been sceptical of whether there is any real advantage to ‘functionally graded’ materials, but the squid beak turned me into a believer,” says Zok, a materials scientist at UC Santa Barbara. “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 –– that has the consistency of Jell-o.”
The findings could be useful in medicine, when hard implants are incorporated into soft tissue, he suggests (Quad-City Times).
Herb Waite, Zok’s co-author, notes, “Squids can be aggressive, whimsical, suddenly mean, and they are always hungry. You wouldn’t want to be diving next to one. A dozen of them could eat you, or really hurt you a lot.”
Ed Yong has a nice post about this research with more on the Humboldt, including links to some awesome stuff on camera man Scott Cassell. When you read this extract, bear in mind that Cassell isn’t some squirrelly amateur diver – he’s an ex special forces professional:
As Cassell tells it, one attacked his camera, which smashed into his face, while another wrapped itself around his head and yanked hard on his right arm, dislocating his shoulder. A third bit into his chest, and as he tried to protect himself he was gang-dragged so quickly from 30 to 70 feet that he didn’t have time to equalize properly, and his right eardrum ruptured.
Image top: It will eat you if it gets a chance / NOAA
Image bottom: The beak in question / Science