Researchers have found 16 species of so-called ultra-black fish, which by definition absorb more than 99.5 percent of light, making them mere shadows as they swim, scientists wrote in a study published Thursday in the journal Current Biology, according to The New York Times.
“In the deep, open ocean, there is nowhere to hide and a lot of hungry predators,” zoologist Karen Osborn of the Smithsonian’s National Museum of Natural History and a co-author of the study, said, according to Reuters. “An animal’s only option is to blend in with the background.”
And while little light penetrates below 650 feet, some of the ultra-black fish live three miles underneath the surface, according to Reuters.
As the species evolved, they modified the pigment of their skin through continuous layers of melanosomes, which store light-absorbing melanin, to more easily hide from predators, The Times reported. “It’s like looking at a black hole,” Duke University biologist Alexander Davis, a co-author of the study, told The newspaper.
One bioluminescent anglerfish documented by the team absorbs an astounding 99.95 percent of light, making the fish virtually invisible.
Prosanta Chakrabarty, a biologist at Louisiana State University who wasn’t involved in the study, told The Times, “I would not be surprised if we have not yet found the blackest fish in the sea.”
Other species documented in the study include the fangtooth, the black swallower, and the Pacific blackdragon, according to Reuters.