This mackerel comes from more than 3,000 meters deep in the eastern Atlantic Ocean.
Photograph by Sonke Johnsen
In the darkness of the depths of the ocean, fish have to "wear black clothes" to blend into the night in order to avoid predators.
Written by: ELIZABETH ANNE BROWN
In the vast, dark deep sea, the camouflage of fish is ever-changing, but there is one trick that can be said to be tried and tested, that is, the black appearance that blends into the dark environment.
Some fish, including vipers, have evolved to become darker and darker, appearing to be cloaked in invisibility in the deep sea.
"When you encounter vipers in the water, they are like black holes in the universe, and the body color is beyond your usual definition of black." Sönke Johnsen, a marine biologist at Duke University in the United States, says he specializes in these inhabitants of the deep sea.
Scientists have been studying the "ultra-blackfish," the creatures of the deep sea that absorb light so much, to figure out how they made themselves so invisible.
Recently, Johnsen and colleague Karen Osborn discovered that the skin of these deep-sea fish has extremely complex nanostructures that can capture incoming photons and absorb almost all of them. In January, the team presented the results at the Annual Meeting of the Society for Integrative and Comparative Biology.
"We thought we'd only find a lot of pigmentation," says Osborn, an invertebrate at the Smithsonian National Museum of Natural History, "and we found coordinated physiological tissue that makes the fish look super black." ”
Why do they play tricks in the dark deep sea?
Deep-sea pinball table
The deep sea is a food-starved area, and each member is a recipe dish. Fish such as anglerfish have evolved a whole set of "weapons" to catch prey; some fish use their tentacles to find moving prey; and others use luminous organs to sweep around.
"Imagine a scene like this, shining it with a flashlight and not seeing anything out of the ordinary," Johnsen says, "only occasionally being hit by something, as if radar could detect its existence." ”
The most basic defense of deep-sea fish is to imitate endless seawater. "You only have to carefully explore the waters illuminated by the lighting fixtures to know what's there."
Pacific True GiantMounts live near the Hawaiian Islands.
According to Johnsen, in order to absorb all the incident light, it is not enough to rely on a large amount of melanin alone, the key is to look at the surface of the skin.
If a fish's skin structure is too simple and smooth, the predator will see a bright image. However, if the structure of the surface of the skin is more complicated, then the incoming photons will hit the wall and bounce like a marble on the marble.
Osborn studied the skin surface structure of 7 species of ultra-blackfish in recent trials, all of which come from the wild. She found tiny melanin sacs, which are very similar to those in the human body, and they are arranged in an extremely complex arrangement from the microscopic structure, as if they were a super difficult pinball table game. Incoming light comes and goes.
According to johnsen and Osborne's research, some ultra-blackfish can absorb 99.9% of the incident light, which means that only one in a thousand photons escape the maze.
How black are the "blackest" fish?
This makes the ultra-blackfish one of the "blackest" creatures known in the world, or the most capable of absorbing incident light.
The world's "blackest" biological organ is the black feathers of the Australian Bird of Paradise, with an absorption rate of up to 99.95%.
Scientists believe that the reason why the feathers of male birds of paradise have evolved to become more and more "black" is because the darker they are, the more they can set off the colorful spots on the feathers, which helps to achieve its ultimate goal - to attract the opposite sex.
The mechanism by which deep-sea fish absorb light has caught the eye of Yale ornithologist Richard Prum.
"Microscopic caves on bird feathers and butterfly scales capture photons," Prum explains, "while super-blackfish use the microscopic structure of the pigment sac to absorb light." ”
This unique construction is the focus of scientists' attention, and it has helped to develop biomimetic ultra-black products, including cameras, telescopes and solar panels, especially high-tech products that are currently too expensive.
I hope that this "super black" mackerel will bring us the opportunity for technological revolution.
(Translator: Kiyozumi Shikami)