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Karen Osborn / Smithsonian
The ultra black Pacific black dragon is a very difficult animal to photograph
An oceanic mystery, how the blackest fish in the deep sea are so extremely black, has been solved in a study that started with a very bad photograph.
“I couldn’t get a good shot, just silhouettes of fish,” said Dr. Karen Osborn of the Smithsonian Institution.
His detailed study of the animal’s “ultra black” skin revealed that it catches light.
While it makes animals difficult to photograph, marine scientists say it provides the ultimate camouflage.
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Karen Osborn / Smithsonian
The discovery, described in the journal Current Biology, could provide the basis for new ultra-black materials, such as coatings for the interior of telescopes or cameras.
Several ultra black species, according to research, appear to have independently developed the same trick.
“The pigment particles in your skin are the right size and shape to scatter any light they don’t absorb laterally,” said Dr. Osborn of the Smithsonian’s National Museum of Natural History in Washington DC.
These pigment particles are arranged in a densely packed, thin layer. “So instead of returning the light, they scatter it back into the layer, it’s a light trap.”
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Karen Osborn / Smithsonian
Several deep-sea species have independently developed the same light-trapping skin structures.
It was Dr. Osborn’s frustrated efforts to take good pictures of the deep sea species she was studying that inspired her and her colleagues to look much closer, on a microscopic scale.
“Every picture I took was really bad, it was very frustrating,” he told BBC News. “[Then] I realized that they had really strange skin: they are so black that they absorb all the light “.
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Karen Osborn / Smithsonian
Light-catching skin provides extremely effective camouflage in the deep sea.
This light-trapping skin, researchers say, is the ultimate in deep-water camouflage, where there is very little light, but where other species, including predators, produce their own bioluminescent light.
“You don’t know where that light will come from,” Dr. Osborn explained. “So living in the depths of the sea is like playing hide and seek on a soccer field: the best thing to do is to turn green and lie down as flat as possible.”
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Karen Osborn / Smithsonian
“Being so black really helps these creatures survive.”
His efforts to capture beautifully clear images of these ultra-black species, all of which live in ocean depths of more than 200 m, finally paid off.
“A lot of special lighting was needed,” he admitted. “And a lot of Photoshop.”
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