Researchers Study How Marine Animals Become Invisible

Invisibility might not be the exclusive realm of “Harry Potter” characters anymore. Researchers are currently looking at how marine animals use camouflage to hide from predators so they can one day apply it to artificial technologies.

With a grant from the U.S. Department of Defense and Office of Naval Research, scientists at the Scripps Institution of Oceanography — along with Duke University’s biology department and UC Santa Barbara’s Marine Science Institute — are studying how squids and octopuses use light-sensitive cells to camouflage themselves in different ocean conditions, like sea floors and coral reefs.

Even while moving, a cuttlefish can change its colors to match its surroundings. The octopus can use muscles under its skin to imitate external textures and blend in.

“The animals use camouflage because they obviously don’t want the predators to see them and eat them,” Scripps professor Dariusz Stramski said. “If there is an octopus swimming over the bottom of the ocean … it can quite easily quickly adjust its colors and reflections from its skin that’s almost impossible to distinguish it from the area over which this animal is sitting.”

Squids and octopuses can expand or contract their muscles, using chromatophoric cells to produce pigments that change the color and texture of their skins. They also release pigments at different rates and patterns to adjust how fast they camouflage.

Now in their second year of research, the scientists will focus on the animals’ abilities to avoid detection based on color, reflection and bioluminescence. They will look at how different ocean depths affect animal camouflage behavior and the animals’ ability to perceive when they should assume their camouflage.

The researchers use a Holodeck — a tank surrounded by six screens that recreate different light conditions of the ocean — and an Omnicam to observe how two species of squid and one octopus species behave.

Stramski’s team will develop new optical instruments to measure the speed, distance and intensity of light and to determine what colors are emitted underwater.

“My team provides expertise in measurements and characterization of underwater lights,” Stramski said. “To understand how animals camouflage themselves, we have to have a good understanding of how light works in water and how animals perceive it.”

“If we can understand the mechanisms that animals use to camouflage themselves or become invisible in the natural world, then potentially this understanding can provide us with some guidance on how to create artificial technologies that can lead to camouflage,” Stramski said.

Readers can contact Regina Ip at [email protected].

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