Opalescent shore squid (Doryteuthis opalescens) are some of the most interesting shapes on Earth. These strange cephalopods are covered in a special skin that can be precisely attached to a kaleidoscope of dyes.
Scientists have been fascinated by the mockery and amazing communication of this squid. New research has taken us even closer to discovering how they can remove such attractive clothing that allows them to hunt near the brightness of the shore, slipping with unprecedented predators, or even avoiding aggressive attackers by spraying a pair of fake credentials.
Previous studies have shown that the opalescent squid has a complex molecular device within its skin: a thin film of stack cells that is able to expand and contract as a box to reveal the entire light spectrum, from red and orange to yellow and green, to blue and violet.
These small grooves are similar to what you see on a circular plate, researchers say, showing a rainbow of colors as you press it under the light. But just like a CD, this skin also needs something to enhance its colorful sound.
When researchers tried to genetically engineer the skin of this squid, they noticed that there was something a bit off.
The ‘motor’ that tightens the grooves inside the skin of the squid is driven by reflectin proteins, which respond to various cloud signals and control reflective pigment cells.
Synthetic materials containing reflectin proteins have shown an iridescent appearance similar to what we see in gibberish, but these materials could not bounce or move in the same way.
Something was clearly missing, and recent studies inside live squirrels and genetic engineering have shed light on their mysteries. As it turns out, reflectin proteins can only shine if they are enclosed in a reflective reflective envelope.
It is this envelope that encircles the box-like structure, and looking below, you can begin to see how it works.
Reflectin proteins are usually reactivated by each other, but a neuronal signal from the squid’s brain can offset that progressive charge, allowing the proteins to clump tightly together.
When this happens, it irritates the overlying membrane to push water out of the cell, reducing the thickness and width of the grooves, which scatter light into different colors.
This drop between the grooves also increases the density of reflectin, which allows the light to appear even brighter.
Thus, the authors explain, this “complex process” is dynamic [tunes] the color and at the same time increases the intensity of the re-exposed light “, and this is what allows the opalescent squid to be brighter and thinner, sometimes with color and sometimes not.
Cells inside the squid’s skin, which reflect only white light, appear to be controlled by that same molecular mechanism. In fact, the authors believe that this is what allows the squirrel to see the bright or dark sunlight on waves.
“Evolution has optimized not only the color tuning, but the brightness using the same material, the same protein, and the same equipment,” says the biochemist. Daniel Morse of the University of California, Santa Barbara.
Engineers have been trying for years to mimic the amazing skin of the opalescent squid but never got there. The new research, backed by the U.S. Office of Arms Research, has helped us figure out where we were going wrong.
For their own sake, thin films of reflectin cannot deliver the full power of light control that we see in a cable, the authors conclude, because we do not seem to have that twin amplifier .
“Without that membrane around the reflectins, there is no change in the brightness of these artificial thin films,” Morse says.
“If we want to capture biological power, we need to introduce some sort of organ-like circulation to allow back-up clearance to be clear.”
The study was published in Applied Physics Letters.