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Hark! Glow-In-The-Dark Shark Sparks Biology Landmark

MARY LOUISE KELLY, HOST:

Jerome Mallefet was about to call it quits. For a month, he had worked 12-hour shifts seven days a week on a boat off the coast of New Zealand. Then, just as he was packing up, he stepped into his laboratory aboard the boat one last time.

JEROME MALLEFET: I went into the dark, and I said, gosh, it's glowing like hell. Woah, I said, yes, I got it (ph). To see it, I was just like a kid in front of a Christmas tree.

AUDIE CORNISH, HOST:

What he saw was a shark glowing in the dark. You see, Mallefet studies bioluminescence, the ability of living organisms to create their own light. He says sharks light up for all sorts of reasons.

MALLEFET: Sharks are the MacGyvers of bioluminescence use.

CORNISH: They use it to warn predators or to recognize their kind or to camouflage their silhouettes against the faint blue glow of the ocean's surface.

KELLY: Glowing sharks were first documented back in the 19th century. Scientists estimated that about five dozen of the world's more than 500 shark species glowed, but only a handful had been confirmed. Mallefet was determined to add to that list.

CORNISH: So he hitched a ride on a fishing boat to study sharks accidentally pulled up in its nets, and he was able to document for the first time the glow of the kitefin shark. At nearly six feet long, it's the largest glow-in-the-dark vertebrate known to science.

MALLEFET: It's not the discovery of a new species, but it's showing that it's really luminous. And it's the discovery of the pattern.

CORNISH: The work appears in the journal Frontiers in Marine Science.

KELLY: Steve Haddock at the Monterey Bay Aquarium Research Institute was not involved in this work, but he did recently document a glow-in-the-dark sea sponge. He says these recent discoveries underline just how popular the strategy is for deep-sea dwellers.

STEVE HADDOCK: It's super-widespread. It arose at least 50 times across the tree of life. That, to me, suggests that it's actually relatively easy to evolve it. It seems like this really crazy, magical thing, but the mechanisms to get light out from a cell evolutionarily must not be that complex.

CORNISH: Not that complex for sharks, maybe. But we humans still haven't figured out how to glow.

MALLEFET: I'm not jealous, not at all. But I'm really respectful of all those organisms. They are able to produce light. We are not. The shark is brighter than me. He can glow. I cannot.

KELLY: Marine biologist and shark watcher Jerome Mallefet of the University of Louvain in Belgium.

(SOUNDBITE OF SVEN LIBAEK'S "ATTACKING SHARKS") Transcript provided by NPR, Copyright NPR.