Militaries Study Animals for Cutting-Edge Camouflage

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"If you know how to manipulate the way light moves and reflects then you can make a surface brighter or darker," he said.

Other butterfly species are able to produce different types of iridescence.

"If nature evolved blue morpho butterflies to be bright and blue, all it has to do to that scale structure is tweak it slightly, alter the dimensions, and it produces a different color such as green," Vukusic said.

The challenge for scientists like Vukusic is to create a surface able to reflect different colors of the light spectrum, a surface able to mimic its surroundings, so providing a cloak of invisibility for troops and their weapons.

Vukusic believes moths could provide a similar template for nighttime camouflage.

Moths have evolved modifications in their wing scales that swallow up light so their wings appear black.

"Instead of multilayers, some types of moth wing have thousands of tiny, nipple-shaped structures arranged in a hexagonal array. If they are really small, half the wavelength of light, then their effect is to reduce reflection from the wing surface," Vukusic said.

The scientist also speculates about the possibility of being able to design a surface that is black at different wavelengths. So instead of being black visibly, it would be black at infrared, making it invisible to certain types of military night-vision equipment. "If we understand how nature does this, in theory it would be possible to change the dimensions of the structure to make it appropriate for infrared anti-reflection," said Vukusic.

Bio-camouflage System

Below the waves, kaleidoscopic cuttlefish match the blue morpho's electric display. They can rapidly alter their vivid coloring to blend into the background. This helps them escape predators and ambush their prey.

English-based scientists are developing a bio-camouflage system based on the color-generating abilities of cuttlefish. Applied as a gel, it could be used to hide tanks and other military equipment.

Alex Parfitt, from Bath University's Centre for Biomimetics and Natural Technologies, in England, said: "The cuttlefish is the fastest color-changing animal on the planet. But when we looked at it a little deeper the system was far simpler than we expected."

Just below the skin are organs called chromatophores. They consist of little elastic sacs filled with pigment. An attached muscle allows these to contract or expand, triggering an instant change of appearance. "You can think of it like controlling pixel size," Parfitt said.

But the cuttlefish holds just three colors in its chromatophores: brown, red, and orange. Although these can be stretched into other shades like beige, pink, and yellow, the animal has another trick up its sleeve when swimming in places that are mainly green or blue.

Contained deeper under the skin are white patches which include cells called leucophores. These reflect back the predominant light wavelength in the cuttlefish's immediate environment.

"So if a cuttlefish swims along under green seaweed, the green wavelength coming from it will hit the cuttlefish and be reflected back," Parfitt said. "It's like a sort of mirror system. Without even thinking about it the animal is able to camouflage itself really well."

Parfitt and his colleagues have now come up with a color-changing gel based on the cuttlefish's light-reflecting system. It could even replace the traditional green-and-brown camouflage splotches used on military equipment since the First World War.

In warfare, as in nature, you have to evolve to stay ahead of the game. So it's no wonder the scientists are turning to the natural world for inspiration.

As Peter Vukusic says, "it's all out there—nature has absolutely beaten us to every structure we think we've designed."

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