Deep Sea Ultra-Black Fish

Overview

• Below 200 meters in the ocean, there is almost no sunlight.
• Many creatures produce bioluminescence to lure or expose prey.
• Some fish have evolved to absorb almost all light, making them nearly invisible in the deep sea.

Study Findings (July 2020)

• Published in Current Biology.
• 16 species of fish absorb more than 99% of light.
• Fish species are often distantly related.
• Evolution favors extreme darkness to avoid predators.

Characteristics of Ultra-Black Fish

• These fish absorb light to become nearly invisible.
• One species absorbs 99.95% of light.
• Ultra-black coloration is different from ordinary black.

Mechanism Behind Their Darkness

• Fish use melanin pigment packed tightly in structures called melanosomes.
• Melanosomes prevent light from reaching non-pigmented cells.
• Light that isn't absorbed immediately gets scattered into other melanosomes.
• Skin acts as an endlessly absorbing layer of darkness.

Predator Avoidance

• Darkness helps fish hide from bioluminescent predators.
• Some fish have ultra-black pigmentation in their gut to avoid glowing bellies.

Applications on Land

• Engineers are interested in ultra-black materials for cameras, optics, and space instruments.
• Current ultra-black materials are complicated to manufacture.
• Fish might inspire new, simpler designs for ultra-black materials.

Further Learning

• More information available in a SciShow episode about the darkest material ever made.