Ultra-black skin allows some fish to blend into the cold ocean depths

There's a fish that lives in the ocean depths called the dragonfish or the common fangtooth. The fish lives in the depths of the ocean where there's nothing to hide behind to escape predators, and there is no sunlight. To help keep the fish out of sight in the glow of bioluminescent organisms that hunt at that depth, they have ultra-black skin that allows them to remain unseen.A new report shows that at least 16 species of deep-sea fish have evolved ultra-black skin that absorbs more than 99.5% of the light that hits them, making them nearly impossible to see in the dark ocean depths. What allows the fish to disappear so efficiently are tiny packets of pigment inside their skin cells called melanosomes. Those pigment packages are differently shaped and arranged on a microscopic level for the ultra-black fish than they are with regular fish.

Researchers studying the fish say that the information could lead to new light-trapping materials that could be used in all manner of applications from solar panels to telescopes. For the study, the team used a net and a remotely operated vehicle to capture 39 black fish swimming up to a mile under the waters of Monterey Bay and the Gulf of Mexico.

Researchers used a spectrometer to measure the amount of light reflected by the fish's skin and identified 16 species that reflected less than 0.5% of light. That makes them about 20 times darker and less reflective than everyday black objects. The darkest species they found was an angler fish not much longer than a golf tee.

That particular fish reflected only 0.04 percent of the light back to the eye of predators in the deep. The only other creature known to match the super dark fish are birds-of-paradise from Papa New Guinea that have ultra-dark plumage. Interestingly, the team had a difficult time taking photos of the fish on the boat for their research because no matter what lighting was set up, it was nearly impossible to capture features of the fish in photos.