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Go to CuriosityStream.com/SciShow to learn more. [♪ INTRO]. Cuttlefish are the ultimate hide-and-seek players.

They can copy the color, contrast, even texture of their surroundings in seconds— even in the dark of night. They are camouflage wizards! And what makes their skill absolutely mind blowing is that they can do this even though they are colorblind.

We've actually known for some time that cuttlefish are colorblind. Heated debates in the early part of the 20th century were basically settled when biologists dissected cuttlefish eyes and found only one visual pigment—which would strongly suggest that they could only see in black and white. Still, just to make extra sure, though, scientists in recent years have tested their camouflage abilities on a series of checkerboard patterns of various colors and brightnesses.

And when the colors are matched in intensity, the cuttlefish don't blend in, further implying they can't see the difference between those colors. The conundrum of how cuttlefish and other cephalopods – like octopus and squid – can copy colorful patterns without being able to see them has perplexed scientists for decades and led to some wild theories. Like, one is that cuttlefish see with their skin rather than their eyes ... which actually isn't as out there as you might think.

Cuttlefish do have light-sensitive proteins, called opsins, all over their skin. Opsins are the molecules in eyes that detect light, so researchers thought that maybe they gave the animals' skin a kind of “sight”—enough to figure out the colors they needed to blend in with, anyway. And this theory /would/ kinda explain a study done back in 1930 which found that cephalopods could still change color even if one or both their eyes were removed – although the paper says the ability was “somewhat impaired”.

But, despite five years of painstaking research, scientists haven't found any conclusive evidence that these opsin proteins have any connection to their camouflage abilities. So in 2016, scientists put forward a new hypothesis that got some tentacles in a bunch. They argued the cuttlefish aren't quite as colorblind as they seem, and that they're actually able to discern colors using chromatic aberration.

That's the phenomenon where different colors of light come into focus at different distances because of the way different wavelengths of light bend through a lens. It's actually an annoying thing that happens with cameras sometimes, producing a rainbowy edge to pictures. And it turns out that eyes with off-center pupils – like cuttlefish have – create the same kind of chromatic aberration as camera lenses, but more strongly.

If the cuttlefish can essentially shift their focus and use this trick to separate reds, yellows, and blues, then they wouldn't actually need to see color directly to sense it for their patterning. The problem is, so far, this has only been tested using computer models, so many scientists are still skeptical. And really, neither of these ideas provides a satisfactory explanation for how the animals can camouflage themselves at night when there's basically no light for them to pick up.

So for now, it seems that how colorblind cephalopods manage to be masters of disguise will remain a mystery. Which makes it, to me at least, that much more impressive. If you love learning about the quirks of life on this planet—and, we're guessing that you do, since you are watching SciShow right now—then we think you might enjoy the videos offered over at CuriosityStream.

CuriosityStream is a subscription streaming service that offers over 2000 documentaries and non­fiction titles from some of the world's best filmmakers, including exclusive originals. They have videos on nature, history, technology — even society and lifestyles — which is one of the reasons that we love them so much. If you liked this episode on cuttlefish, you might like the documentary

Dazzle: The Hidden. Story Of Camouflage. It goes over the history of camouflage, including how engineers are trying to take inspiration from animals like cuttlefish to create stealthier ships or even invisibility cloaks. You can get unlimited access to content like this starting at $2.99 a month.

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