Octopuses, squid, and cuttlefish are true masters of disguise. In the blink of an eye, these sneaky cephalopods can match their own color to the environment around them and seemingly become invisible to their enemies.
The US Army has recently teamed up with chemists at Northeastern University to look at this incredible class of animal for inspiration for a new form of color-shifting camouflage that can be applied to textiles or color-changing objects. Their research was published in the journal Advanced Optical Materials.
Squid skin appears to change color thanks to red, yellow, brown, and orange cells called chromatophores. These features are dotted along the skin of the cephalopod, constantly getting larger and then smaller. This gives the impression of a continuously altering skin color. Beneath the chromatophores, there’s another layer of super-reflective iridophores that are able to scatter and reflect all visible and infrared light. Together, these features can drastically shape the way color is reflected off the animal and then perceived.
The researchers started by removing and analyzing an individual pigment particle from the squid that was no larger than 500 nanometers in size. Inspired by its structure, they began to craft a similar material that consists of iridescent-like threads (image below) that the researchers describe as "really rich in colors".
“From a scientific and technical engineering perspective, understanding how light scattering affects color is very important, and this is an exciting new development in the field of optics in biology,” Richard Osgood, a collaborator from the US Army Natick Soldier Research, Development, and Engineering Center, said in a statement. “This is an unusual harnessing of optics and physics knowledge in scattering to understand biological systems.”
The researchers made spools of fibers from the squids' pigment particles. They’re now looking into how they can weave these fibers into textiles or other mediums to give the impression of color-changing camouflage, just like a frightened cephalopod.
Who knows, perhaps the soldiers of the future could be armed with a uniform heavily inspired by the humble cuttlefish.
"For more than a decade, scientists and engineers have been trying to replicate this process and build these devices that can color match, color change, and camouflage just like the cephalopods, but many of them come nowhere near the speed or dynamic range of color that the animals can display," added Leila Deravi, assistant professor of chemistry and chemical biology at Northeastern. "Cephalopods have evolved to incorporate these specific pigment granules for a reason, and we're starting to piece together what that reason is."