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Holy camouflage, Batman: We now know the secret behind these deep-sea creatures' built-in Batsuits

Contributed by
Jul 26, 2020

It seems that even the Dark Knight’s body armor doesn't blend into the night enough to be the ultimate stealth suit in impenetrable darkness.

Batman has nothing on some species of fish that lurk at the bottom of the ocean. He should ditch Robin and make some of them his minions. With “ultra-black” skin that absorbs up to 96% of visible light, these fish have built-in protection from predators and no problem sneaking up on prey. Now that biologist Alexander Davis and his team of researchers were somehow able to find these fish in the eldritch depths and observe their powers of invisibility under a microscope, we may have what we need to someday develop a Batsuit that eludes even the Joker.

“Pressure to reduce reflected bioluminescence led to the evolution of ultra-black skin,” Davis said in a study recently published in Cell.

The hadal zone of the ocean breeds all sorts of bizarre creatures. Those that are bioluminescent glow in the dark, which makes them visible to each other in a place no sunlight can reach. Bioluminescence can also act as a flashlight that reflects off predators in the dark. When you live in such a brutal and unforgiving place (kind of like Gotham City), you need every defense you can get, and being able to light up doesn't hurt. However, there are other fish that stay alive by doing the exact opposite. Some of them are ultra-black all over. One bizarre species is transparent with the pigment only on its stomach, suggesting that it drowns out the light of any bioluminescent prey it eats.

As Davis and his team studied the fishes’ skin up close with regular and electron microscopes, they found that their structural camouflage differs from just any black pigment. Nine of the 16 species they brought to the surface exhibited a layer of melanosomes that were structured and packed unlike the black pigment in something like a bat or a raven. Animals that are darkly pigmented normally have spherical melanosomes, or structures that contain melanin—the same pigment found in human skin. The downside of these melanosomes is that their shape allows for unpigmented gaps that allow for some reflection. Ultra-black melanosomes are ellipsoid, or oblong, which means they can be packed so closely together that almost no light can pass through.

“The melanosome layer produces low reflectance by scattering light sideways within the layer, thus increasing the path length for light absorption,” Davis said, adding that “the melanosomes in ultra-black fish are well optimized for producing low reflectance.”

So the skin of these fish basically eats almost all light. Reflection happens when light bounces off an object, but the melanosome layers of the fangtooth, dragonfish, and other species that convergently evolved to absorb the light that would otherwise bounce off and reveal them to both predators that would hunt them and prey that would swim away. The small size of most of these fishes is also an advantage since they are already difficult to spot from a distance, and the extreme camouflage makes them vanish into the chasm they live in and, as the team found, nearly impossible to image with even the most advanced cameras. Oneirodes, a tiny but fierce anglerfish, was the blackest one found and possibly the darkest creature on Earth. Hungry predators or fearful prey would have to be extremely close to these species to glimpse it, because moving just slightly away would make it invisible.

Just imagine something with a gaping mouth and enormous fangs was right behind you and you had no way of seeing it. The understanding of how ultra-black skin is structured could eventually upgrade materials worn on human stealth operations. Scientists were able find out how to mimic the microstructures that make cephalopods blend into their environment and turn it into one type of stealth suit material, so man-made ultra-black fabrics could happen.

Batman would have an unbeatable Batsuit. Searching through darkness to find darkness can take a while. If more of these creatures exist, they literally haven’t been seen yet.

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