Squid Skin Secrets: Iridescence Explained

Researcher have long known that squids are particularly good at manipulating light - reflecting what sunlight trickles down into the ocean's deeper depths in order to confuse predators, prey, and even to communicate.  Now a team of scientists has determined just what kind of mechanisms make squids such masters of light - information that could prove useful even for engineers.

That's at least according to a study recently published the Journal of Biological Chemistry, which details how squids can "tune" the color they reflect by activating specific sequences of reflectins, proteins unique to the light-sensing tissue of cephalopods.

Past work has show us that unlike the famous cuttlefish, the pigment cells of squids are not ridiculously complicated in their design.

However, researchers also know that squids like the California market squid (Doryteuthis opalescens) are able to present their skin in a surprising number of hues. According to Daniel Morse, a researcher with the University of California, Santa Barbara, it's not so much about pigment as it is about structural reflection.

[ This is not unlike the mechanism of chameleon skin, which uses both complex pigment changes and  reflective properties to achieve amazing camouflage accuracy. Check that out here. ]

"The discovery reported in this paper reveals the subtlety and power of the reflectin proteins to fine-tune the colors of living cells with a beauty that reminds us of paintings by Monet," Morse, who co-authored the study, said in a statement.

Specifically, the researchers determined that there are three major type of reflectins, all of which influence one another and likewise influence the surface membrane of squid cells, influencing how they reflect light.

"It's a very complicated system," lead author Daniel DeMartini added. "In the future, this [understanding] could be very useful for creating synthetic optical materials that - like squid skin - can be tuned."

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