The Washington PostDemocracy Dies in Darkness

Octopuses don’t really need eyes to ‘see’ light: They have sensors in their skin, study says

This video from marine biologist Roger Hanlon shows an octopus coming out of camouflage in reverse slow motion to better demonstrate the incredible transformation. (Video: Courtesy of Roger Hanlon)
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Octopuses:They're the slightly terrifying, two-eyed, eight-armed sea creatures you probably don't know much about.

I mean, who among us hasn't wondered: What is an octopus, even?

That's okay, because science is just starting to really figure them out, too.

I'm not here to answer all of your questions — just this one: How are these creatures able to famously change the color, pattern and texture of their skin to camouflage themselves in response to their environment?

A new study from researchers at the University of California at Santa Barbara sheds light (pun intended) on that very question.

It turns out that despite the fact that octopuses have eyes and brains (which  they actually put to good use) — not to mention several hearts — they actually don't need to use those to sense changes in light around them.

Their skin tissue can do that all on their own.

[The octopus that figured out how to work a camera]

"Octopus skin doesn't sense light in the same amount of detail as the animal does when it uses its eyes and brain," said lead author Desmond Ramirez, a doctoral student in the UCSB Department of Ecology, Evolution and Marine Biology. “But it can sense an increase or change in light. Its skin is not detecting contrast and edge but rather brightness.”

To test this, researchers exposed the octopus skin to different kinds of light. They found that that in response to light, the organ that expands or contracts to change the color of the octopus's skin, or chromatophores, expanded and changed color. They call the process Light-Activated Chromatophore Expansion or LACE.

[Watch the first-ever video of octopus cannibalism]

In octopuses' skin tissue, researchers found a protein that is usually found in its eye, leading them to believe that the animals have evolved to use the same mechanism for light detection in both places.

“It looks like the existing cellular mechanism for light detection in octopus eyes, which has been around for quite some time, has been co-opted for light sensing in the animal’s skin and used for LACE,” explained co-author and UCSB professor Todd Oakley. “So instead of completely inventing new things, LACE puts parts together in new ways and combinations.”

Octopuses aren't the only mollusks that do this sort of thing. But these findings do help to piece together more about the octopuses evolutionary relatives.

And the animals' unique skill at camouflage is something that could potentially have big implications for us humans, who are, of course, trying to figure out how to make synthetic materials that mimic the octopuses' signature talent.