Bizarre Camouflage Skills of the Cuttlefish Have Finally Been Explained by Science

Here a cuttlefish can be seen camouflaging itself against the algae-covered rocks that surround it. Roger Hanlon

The animal kingdom is home to all manner of weird and wonderful defense tactics, but the camouflage skills of cuttlefish, squid and octopuses surely rank among the most impressive.These masters of disguise have the incredible ability to change the color or texture of their skin spontaneously, enabling them to hide effectively when danger looms.

And among the most striking such traits is the ability of the cuttlefish to erect small spikes on their skin that mimic coral or other objects in their environment.

Exactly how the cephalopod manages this feat has long puzzled scientists. But thanks to new research, published in the journal iScience, marine biologists from the University of Cambridge and the Marine Biological Laboratory at the University of Chicago have uncovered fascinating details about the underlying biological mechanisms that produce this effect.

"The biggest surprise for us was to see that these skin spikes, called papillae, can hold their shape in the extended position for more than an hour, without neural signals controlling them," Paloma Gonzalez-Bellido, from the University of Cambridge, an author of the study, said in a statement.

The mechanism bears an intriguing resemblance to another seen in clams. Those shellfish snap their shells shut when they feel threatened by using a specialized muscle. In cuttlefish, a similar muscle inside the papillae enables the spikes to remain erect for extended periods

Read more: Dozens of octopuses crawl from the sea in Wales in 'end of days' beach science

In clams, these muscles remain locked in a tense state until a chemical signal releases them, causing the shell to shut rapidly without using up any energy. The cuttlefish have a similar biological process, the researchers found.

Gonzalez-Bellido and her colleague Trevor Wardill wanted to know how the cuttlefish control the papillae neurologically. According to their findings, a nerve originating in a region known as the stellate ganglion is exclusively dedicated to managing the papillae.

And it turns out that the neural mechanisms that control the papillae in cuttlefish are surprisingly similar to the nerve circuits in squid that control skin iridescence. Because squid don't have papillae and cuttlefish don't have tunable skin iridescence, the scientists theorize that these neural circuits evolved in a common ancestor.

A close-up of the skin of the European cuttlefish. Paloma Gonzalez-Bellido