Sea creatures of Alabama: Rare pocket shark found in Gulf glows in the dark

Deep within the Gulf of Mexico, there exists a creature so diminutive you could fit it in your pocket or cradle it in your palm. Yet, despite its proximity, you won't encounter this shark off the Alabama coast, and you'll find precious little information on it anywhere else.

A Creature of Mystery

The pocket shark is exceptionally rare, with only two specimens ever documented in recorded history. Greg Graeber, a marine educator at the Dauphin Island Sea Lab, notes the animal's bizarre appearance. It hardly resembles a traditional shark, appearing more like a character from a game or anime than a predator of the deep.

Measuring roughly five inches long, the American pocket shark earns its name from distinct pouches located on each side of its body—though scientists remain uncertain of their specific function. According to Graeber, these sharks feature oversized, rounded heads paired with a pair of small dorsal fins.

Glowing in the Dark

Perhaps the most fascinating trait of this elusive animal is its bioluminescence. Research from Tulane University indicates that these sharks secrete a glowing fluid, likely discharged from their unique pockets to light up the dark, deep-sea environment. Because they inhabit such extreme depths, much of their daily existence—including their mating habits and diet—remains a total mystery to researchers.

From the Pacific to the Gulf

The first-ever specimen was discovered in 1979 in the Pacific Ocean off the coast of Chile and is currently housed at the Zoological Museum in St. Petersburg, Russia. The second encounter occurred in 2010 when scientists aboard the NOAA ship Pisces accidentally caught a pocket shark while gathering data in the Gulf of Mexico.

The shark spent years in a freezer until 2013, when researcher Mark Grace identified the rare find. He eventually arranged for the specimen to be housed in the Royal D. Suttkus Fish Collection at Tulane University.

Following a rigorous study by researchers from Tulane and beyond, it was determined in 2019 that the Gulf-dwelling creature was a distinct species from its Chilean counterpart, leading to its classification as the American Pocket Shark. Evidence indicates that the Gulf species possesses fewer vertebrae and is equipped with light-producing organs known as photophores across its body.

Deep Sea Secrets

While all sharks belong to the cartilaginous family, the Ocean Conservancy notes that only 57 known species have the ability to produce light. Detailed findings on the classification of the American Pocket Shark can be viewed in this report on Zootaxa.

Don't expect to spot one on your next beach day, but if your travels take you into the deep waters beyond the Continental Shelf, keep an eye out for a mysterious glow in the water—you just might be looking at a pocket shark.