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Chameleon Camouflage Crystals: Mysterious Mechanism Revealed

Mar 11, 2015 12:56 PM EDT

Camouflage has always been one of nature's greatest accomplishments in the eyes of man. It's a skill we can barely imitate despite how far technology has come. Now researchers are at least a step closer to understanding how chameleons do it, revealing a stunning and unexpected system just beneath their skin.

Nature World News has previously reported on how squid and cuttlefish change color to blend in with their surroundings and even communicate with one another. This has a lot to do with complex shifts in pigment cells within the skin. A similar mechanism was long thought to be solely behind the incredibly swift and convincing color changes that chameleons pull off, but new research has determined that this is not actually the case.

Unusual crystals, it turns out, actually rearrange themselves just beneath the lizard's skin to reflect a stunning rainbow of colors.

That's at least according to a study recently published in the journal Nature Communications which details how the nanocrystals make up what is best described as a "selective mirror" for light.

This certainly isn't the first time that researchers have stumbled upon nature using something other than pigment to express color. The vibrant blue of blue jays that we see, for instance, is actually just blue light reflected by the unique structure of the bird's feathers. Similarly, the stunning pure white of the Cyphochilus beetle - arguably the purest white in existence - is actually achieved with a shell structure so perfect that it reflects nearly all spectrums of light.

However, what makes the chameleon unique is that it can shift its own unique structures to reflect some colors, even while compensating with additional shifts in pigmentation in the skin - an amazing marriage of abilities that could help pave the way for 'cloaking' technology if experts can better understand it. (Scroll to read on...)

So how does it work? Physicists and biologists at the University of Geneva teamed up to study the crystals in detail, finding that they primarily shift in accordance with how taught or relaxed a chameleon's skin is. This achieves a mirror that will reflect more or less of the light spectrum at one time.

"When the chameleon is clam (loose skin), the [crystals] are organized into a dense network and reflect the blue wavelengths. In contrast, when excited, it lessens its lattice of nanocrystals, which allows the reflection of other colors such as yellows or reds," Jérémie Teyssier and biologist Suzanne Saenko, co-first authors of the study, explained in a statement.

These shifts can only do so much on their own, but it's very likely that they make up for the failings of pigmentation in nature. Researchers have long known that colors like blue and violet, for instance, are rarely expressed by pigment. With the crystals pulling off this side of the task, cells of shifting pigments can take care of the rest, helping craft a rainbow of hues more complex than even humans can see.

What's more, Michel Milinkovitch, the senior researcher on the team, added that these crystals are even used as a "heat shield" at the deeper layers of a chameleon's skin.

"These cells, which contain larger and less ordered crystals, reflect a substantial proportion of the infrared wavelengths," he explained.

This could help hide what little body heat these cold-blooded reptiles have or help maintain a healthy body temperature in sweltering environments.

Still, how these shifts are done to exactly match a chameleon's surroundings or adapt to certain temperatures remains a mystery. That leaves frustrated scientists with a lot left to figure out if they ever hope to make the cloaking tech of science fiction a reality.

For more great nature science stories and general news, please visit our sister site, Headlines and Global News (HNGN).

- follow Brian on Twitter @BS_ButNoBS

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