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Newly discovered shark puts on a light show to lure in its next meal

Christian Cotroneo
July 22, 2019, 1:36 p.m.
The pocket shark was inadvertently collected by the NOAA ship Pisces in 2010. (Photo: Michael Doosey/Tulane University)

Sometimes nature's thoughtfulness seems a little misplaced.

Why, for instance, make a 5-inch shark rarely encountered by humans glow brightly, when there are much bigger, toothier versions that we might appreciate being able to spot from a mile away?

But of course, the newly discovered American pocket shark doesn't care what we think. Its ability to glow in the dark is the ultimate in fast-food convenience.

No more going out for a quick snack. No hanging around corals looking for something to eat. For this shark, dinner is always delivered. It just needs to leave a light on.

In a newly published study from Louisiana's Tulane University, biologists describe a tiny kitefin shark that squirts bioluminescence from its pockets, likely as a lure for smaller fish. The pocket shark — which really should never be placed in your pocket — secretes a glowing fluid from a gland near its front fins. For many bioluminescent marine animals, those flashing lights acts as a beacon for nearby fish that, let's face it, fall for this trick way too often. (For proof, see the horror show that is the black devil angler.)

And just below that cloud of sparkle lurk the jaws of doom. And for good measure, the shark packs its own glow supply — with light-producing organs called photophores covering much of its body.

The study marks the first time this glowing shark has been spotted in the Gulf of Mexico.

"In the history of fisheries science, only two pocket sharks have ever been captured or reported," study co-author Mark Grace, of the National Oceanic and Atmospheric Administration (NOAA), notes in a press release.

Both species of pocket sharks keep their glow juice in pouches located near their gills. (Photo: Mark Grace/NOAA)

The first pocket shark was spotted off the coast of Chile back in 1979. It wasn't classified as a unique species — Mollisquama parini — until five years later.

Similarly, the latest pocket shark discovery — this time in the Gulf of Mexico — took scientists a while to wrap their heads around. It was caught in 2010, but only now described as the new species, Mollisquama mississippiensis.

Unfortunately, as no one realized they were dealing with a new species at the time, neither shark survived being archived. (Photo: Mark Grace/NOAA)

Both shark species produce bioluminous fluid, but the Chilean model is considerably bigger at 16 inches. It also doesn't pack those glittering photophores that make its entire body glow.

Both sharks do, however, spend a lot of time sitting on their tail fins waiting for dinner to come to them.

Which may make you wonder: Wouldn't having dinner delivered every day result in a bigger, chubbier shark? Well, maybe somewhere at the bottom of the Gulf, there is a glowing "Jabba the Hutt."

After all, marine biologists are still far from prying all the secrets from the Gulf's deepest depths.

"The fact that only one pocket shark has ever been reported from the Gulf of Mexico, and that it is a new species, underscores how little we know about the Gulf — especially its deeper waters — and how many additional new species from these waters await discovery," Henry Bart of the Tulane Biodiversity Research Institute, notes in the release.