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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.
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