Pocket Shark Caught off Mexico

Pocket Shark

An exceedingly rare species of shark has finally been identified, a tiny pocket shark caught off the Mexican coast.

During a government research trip in 2010 about 190 miles off the Louisiana coast, a tiny nipper – measuring just 5.5 inches (14 centimeters) long – was caught and its body was frozen while biologists went about identifying it.

Scientists have now identified the mysterious creature to be a pocket shark – a miniature variation of the more popular kinds.

The recent discovery is one of two such sharks reported ever. The first pocket shark was found 36 years ago in the Pacific Ocean off the coast of Peru and it’s been sitting in a Russian museum since.

It’s believed that the newly-discovered pocket shark was just a few weeks old as its size is extremely small and only weighs a mere half ounce. Oddly, this type of shark has two pockets next to its front fins as to which their purpose is unknown.

A genetic analysis of a tissue sample from the Gulf shark suggested it belongs in the Mollisquama genus, and that pocket sharks are closely related to the kitefin and cookie cutter shark species, which are also part of the Dalatiidae family.

A National Oceanic and Atmospheric Administration fisheries biologist Mark Grace has spent more than 30 years going through nets upon nets of fish to identify them.

‘I wasn’t really sure what it was,’ Grace said. ‘That pocket over on the pectoral fin, I had never seen anything like that on a shark.’

Once identified, the shark was shipped to New York and France for high-tech examinations that wouldn’t puncture the specimen.

Pocket Shark

The shark was noticed to have unusual belly patches not seen in more sharks. But the truly strange thing about this species is its twin pockets. Scientists are unsure the exact function of this pocket gland, though in 1984, scientists posited that the opening served to secrete pheromones for mate attraction.

Another idea, Grace said, is that the orifice acts as a source of luminescence. The Mollisquama pocket looks similar to the so-called luminous abdominal pouch on the dalatiid shark Euprotomicroides zantedeschia; that pouch may secrete a luminous fluid to attract prey or mates, or to elude predators, scientists have speculated.

The pocket shark specimen is now part of the Royal D. Suttkus Fish Collection at Tulane University’s Biodiversity research Institute in Belle Chasse, Louisiana.