Two weeks ago, we posted this article about “lost sharks,” which described the challenge of conserving sharks when we know so little about the 1,000 plus species of sharks.
Last week, one of these lost sharks—the pocket shark—was found. A specimen was caught as bycatch in the northern Gulf of Mexico in February 2010, during a NOAA study of sperm whales. It was then added to a specimen collection in their laboratories, where it sat frozen until October 2013, when researchers began studying its genetic and morphological features.
They quickly determined it was a species from the genus Mollisquama, or a pocket shark, related to kitefin and cookiecutter sharks. Remarkably, only one other Mollisquama specimen has ever been found. “The pocket shark we found was only five and a half inches long, and was a recently born male,” says Mark Grace of NOAA Fisheries. “Discovering him has us thinking about where mom and dad may be, and how they got to the Gulf. The only other known specimen was found very far away, off Peru, 36 years ago.”
The shark is not named for its size—though one could fit into your pocket—but rather the distinctive pocket-like orifice behind its pectoral fin. Researchers are unsure what this is for, but hope to examine the specimens further to understand more about these amazing little sharks. In fact, the team isn’t even certain that the new specimen and the specimen discovered in 1984 are the same species “due to differences in tooth morphology and vertebral counts,” according to the study published last week in Zootaxa.
Like the cookiecutter and other Dalatiidae shark species, when hungry, pocket sharks likely remove an oval plug of flesh from their prey (various marine mammals, large fishes and squid). Ouch!
More research is needed on this formerly lost shark, the study’s authors write. “The enigmatic genus Mollisquama has received scant attention from researchers since the southeast Pacific Ocean holotype was described in 1984, but with the capture of a second specimen collected from the Gulf of Mexico additional features not documented for the holotype can now be described.”
“This record of such an unusual and extremely rare fish is exciting, but it’s also an important reminder that we still have much to learn about the species that inhabit our oceans,” lead author Grace says.
Image: Zootaxa, http://dx.doi.org/10.11646/zootaxa.3948.3.10