Above, the sharks as they glow. Below, the sharks as we see them. (Photo: Gruber et al.) 

There’s a group of underwater creatures that, to our human eyes, look pretty dull, but that to other sea life, with the right receptors, give off a brilliant biofluorescence. After a team of scientists found a fluorescent green eel by accident, they started looking to see what other biofluorescent organisms they might be able to discover.

Now, that group includes sharks. As David Gruber, the lead researcher of this project, tells Forbes, some sharks are so fluorescent that they are “as bright as some of the brightest fish, as bright as the corals.”

The species of glowing sharks aren’t the large sharks we tend to talk about. They’re smaller catsharks, and to us they look a dull brownish grey. But they’re actually patterned with neon-green biofluorescence—and the scientists were able to establish that they have receptors in their eyes that allow them to see each other in their full, glowing glory.

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