A tiny shark captured in the Gulf of Mexico was identified as a new species of pocket shark that shoots glow-in-the-dark fluid from pouches near its gills, researchers said.

A team of scientists from universities and research groups around the Gulf and New York identified the 5½-inch male shark as the American pocket shark, or Mollisquama mississippiensis.

The only other pocket shark to be captured was caught in the eastern Pacific Ocean in 1979, but researchers identified five unique features in the male shark that make it a new species.

"In the history of fisheries science, only two pocket sharks have ever been captured or reported," study author Mark Grace of the National Oceanic and Atmospheric Administration said in a statement. "Both are separate species, each from separate oceans. Both are exceedingly rare."

Among the differences between the two species, the newly identified shark has fewer vertebrae and photophores, or light-producing glandular organs, on its body.

Both sharks have pouches near their front fins, but it wasn't until identifying this new species that scientists determined it emits a bioluminescent liquid to attract prey and hide itself.

R. Dean Grubbs, a Florida State University scientist who was not involved in the research, told The Associated Press that this makes it only the third out of 500 shark species that may squirt luminous liquid.

"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," study author Henry Bart of the Tulane Biodiversity Research Institute said in a statement.

The new shark was collected in 2010 during an expedition to study sperm whale feeding. It wasn't until 2013 that the shark was discovered among the specimens. Researchers used various imaging technologies to document the animal and study what it was.

The team's findings were published Thursday in the peer-reviewed journal Zootaxa.

Contributing: The Associated Press. Follow USA TODAY's Ryan Miller on Twitter: @RyanW_Miller