Scientists Find Ocean-Bottom Fish That Gets Ultra-Black as a Defensive Mechanism

Scientists have discovered a new species of fish that turns ultra-black as a defensive mechanism against predators. The rare fish lives in the dark depths of the ocean and has the ability to absorb 99.96% of the light that reaches it at the bottom of the ocean. The scientists found was published in the journal Current Biology.

Researchers said the ultra-black fish changes into a pitch-black color to escape attackers – a camouflage technique that works in the depths of the sea where any fish could be prey to other bigger predators. The ability to become black enables the fish to blend into the dark environments of the ocean depths where it will remain largely unseen by predators or prey until it reaches them.

“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 said. “An animal’s only option is to blend in with the background.”

Scientists likened the evasive fish to the fangtooth, the black dragon of the Pacific Ocean, the anglerfish, and the black swallower among others. These fish are able to change their skin pigment and size as well as shape to defend themselves or escape dangers. Researchers have identified and studied about 16 ultra-black species of dark water fish that evolved to do the same.

Many of these fish live three miles (5,000 meters) deep in the ocean even though sunlight is only able to reach 650 feet (200 meters) below the surface of the ocean. Given the depths of their habitat at the ocean floor, the fish emit light to make them bioluminescence with the sole aim of attracting prey to be eaten. While the light it emits can lure prey for food, it can also scare away predators in some instances.

“This is the second-blackest fish the team found,” the Smithsonian’s National Museum of Natural History tweeted. “It has a bioluminescent lure that it uses to attract prey, and if not for its ultra-black skin and transparent, anti-reflective teeth, the light from its lure would light up its face and scare prey away.”

Scientists said the 16 species of ultra-black fish camouflage themselves so well because of the melanin in their skin. Melanin is the skin pigmentation that makes the human skin dark and these fish appear to have the substance in abundance in their bodies. The pigment absorbs light in the fish to make it ultra-black when it needs to camouflage itself, and also uses the absorbed light to produce its bioluminescence when required.