Ultra-black, light-absorbing fish almost impossible to photograph

CBC Kids News • Published 2020-09-30 13:18

Skin acts like an invisibility cloak

How do you spot something hiding in the darkness?

Easy — you shine a light on it. Duh.

But what if that “something” is disguised as the darkness itself?

In July, scientists at the Smithsonian Institute in Washington, D.C., published new research on a class of deep-sea, ultra-black fish, giving insight into a superpower that makes these fish almost impossible to photograph.

Karen Osborn, a marine scientist involved in the study, said it all started when she was trying to photograph some fish in the deepest, darkest, pitch-black depths of the ocean.

Photo depicts a dark, ghouly fish cast in a tiny amount of light from a camera flash

This ultra-black fish called Anoplogaster cornuta was one of the fish examined to better understand ultra-black camouflage. (Image credit: Karen Osborn/Smithsonian)

“You would crank up the lights and put as many flashes and strobes on it as you could … and still, I couldn't see anything of the fish. I just would get a silhouette,” Osborn told CBC Radio’s As It Happens.

This motivated her and other scientists to find out more about how the inky-black camouflage of these super-fish works.

Light-absorbing suits of ultra-blackness

After studying tissue samples from the fish, scientists discovered that the pigment in their skin gives them the special ability to absorb light.

The ultra-black fish — of which there are many different species — reflect less than five per cent of the light that hits them.

This protects these fish from predators who use light from their bodies to find prey.

Bioluminescent predators

Some predators are bioluminescent, which means they have the ability, like fireflies, to make light with their bodies in the pitch-black depths of the ocean.

Of the 18 species of fish the researchers examined, 16 qualified as ultra-black — meaning that they reflect less than 0.5 per cent of the light that hits them. (Image credit: Karen Osborn/Smithsonian)

Bioluminescent predators shine light on their prey as a way to spot them, just like someone pointing a flashlight on you in the dark.

But that trick doesn’t work as well on ultra-black fish. They just absorb the light.

It’s like they’re wearing aquatic invisibility cloaks. Cool, right?

Scientists trying to harness that superpower

Even more cool is how scientists are trying to steal the superpower for themselves — for good, of course.

Ultra-black materials are already used in telescopes and cameras to get rid of extra light.

Scientists hope to use the research from these fish to make ultra-black materials cheaper and more efficient.


With files from Brandie Weikle/CBC
TOP PHOTO CREDIT: (Image credit: Karen Osborn/Smithsonian)

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