Researchers at the Smithsonian Institution have found deep-sea fish that reflect 99.5% of light. They are difficult to see even in good light; in a little darkness, they simply disappear.

Researchers have discovered one of the blackest materials in the world deep under the ocean – it turned out to be the skin of a deep-sea fish. It absorbs light so much that even in bright light, only the silhouettes of fish are visible without noticeable features. In the dark, even when surrounded by bioluminescent light, they completely disappear.

Scientists have explained this feature of organisms by the unique arrangement of granules in the pigment. It allows some fish to absorb almost all the light that hits their skin – only 0.05% of this light is reflected back. By simulating this, engineers can develop cheaper, more flexible, and more durable black materials for optical technology or camouflage.

Careful laboratory measurements have confirmed that some fish absorb more than 99.5% of the light that hits their surface. In a dark ocean, this intense blackness makes their environment safer.

Most deep-sea creatures, however, produce their own light. Bioluminescent rays are used to attract other animals, distract predators, and lure prey. They can also light up other animals to distract the predator’s attention from themselves.

The researchers noticed that the complete absorption of light by fish depends on the level of melanin, a pigment that colors and protects the skin from sunlight. This pigment is not only found abundantly in the skin of ultra-black fish, it is distributed in a unique way. The pigment-filled cell compartments are tightly packed into pigment cells, and they are located very close to the surface of the fish’s skin.