Opalescent Coastal Squid (Doryteuthis opalescens) are some of the most sophisticated shape changers on Earth. These curious cephalopods are dressed in a special leather, which can be precisely adjusted to a kaleidoscope of colors.
Scientists have long been fascinated by the remarkable camouflage and communication of this squid. New research has brought us even closer to finding out how they can pull off such an eclectic wardrobe, which allows them to hunt near the shore of the shore, slip away from unseen predators or even evade aggressive suitors by flashing a pair of testicles. false.
Previous studies have shown that the opalescent squid has a complex molecular machine in its skin: a thin film of stacked cells capable of expanding and contracting like an accordion to reflect the entire visible spectrum of light, from red and orange to yellow, and green to blue and purple.
These tiny grooves resemble what you see on a compact disc, the researchers say, reflecting a rainbow of colors as you tilt it under the light. But just like a CD, this skin needs something to amplify its colorful noise.
When the researchers tried to genetically design the skin of this squid, they noticed that something was slightly stopped.
The “motor” that regulates squid skin grooves is driven by reflectin proteins, which respond to various neural signals and control reflective pigment cells.
Synthetic materials containing reflectin proteins showed an iridescent appearance similar to what we see in squid, but these materials could not flicker or shimmer in the same way.
Something was clearly missing, and recent studies in live squid and genetic engineering have shed light on the mystery. As it turns out, reflectin proteins can only shine brightly if they are enclosed in an envelope with a reflective membrane.
This envelope is what contains the accordion-like structure and, looking below, you can begin to see how it works.
Reflective proteins are usually rejected by each other, but a neural signal from the squid’s brain can stop that positive charge, allowing the proteins to clump together.
When this happens, it triggers the membrane above to push the water out of the cell, decreasing the thickness and distance of the grooves, which divide the light into different colors.
This collapse between the grooves also increases the concentration of reflectin, which allows light to reflect even more strongly.
Thus, the authors explain, this complex process is “dynamic [tunes] color while simultaneously increasing the intensity of the reflected light, “and this allows opalescent squid to shine and flicker, sometimes with color and sometimes not.
Squid skin cells, which reflect only white light, also appear to be driven by the same molecular mechanism. In fact, the authors believe that this is what allows the squid to mimic the twinkling or dappled light of the sun on the waves.
“Evolution has so beautifully optimized not only color regulation, but brightness regulation using the same material, the same protein, and the same mechanism,” says biochemist Daniel Morse of the University of California, Santa Barbara.
Engineers have been trying for years to mimic the remarkable skin of the opalescent squid, but they never got there. The new research, which was supported by the U.S. Army Research Bureau, helped us figure out where we were wrong.
On their own, thin reflective films cannot give all the power of light control we see in the squid, the authors conclude, because it seems that we lack that coupled amplifier.
“Without that membrane that surrounds the reflectors, there is no change in the brightness of these thin artificial films,” says Morse.
“If we want to capture the power of the biological, we have to include a kind of membrane-like enclosure to allow reversible brightness adjustment.”
The study was published in Letters of applied physics.