The American pocket shark is one of the smallest and most elusive sharks in the ocean. This recently identified species is distinguished by its tiny size and unique biological features. Found in the deep sea, its rarity means that scientific understanding of this animal is just beginning.
Discovery of a New Species
The single known specimen was collected from the Gulf of Mexico in 2010, but it was not formally identified until 2019. Researchers from Tulane University described it as a new species, Mollisquama mississippiensis, after careful anatomical study.
The first pocket shark species, Mollisquama parini, was discovered in the eastern Pacific Ocean in 1979. The Gulf of Mexico specimen was determined to be a distinct species based on several physical traits. The American pocket shark has fewer vertebrae, different tooth morphology, and a different distribution of light-producing organs, called photophores, than its Pacific relative.
Distinctive Anatomy and Abilities
The American pocket shark is very small; the only documented specimen was a young male measuring just 5.5 inches (14 centimeters) long. Its body is cylindrical with a bulbous head, giving it a profile reminiscent of a small whale. The shark’s coloration is a subdued grey, with darker fins and cream-colored patches around its gills.
Its most notable feature is a pair of glands, or “pockets,” situated just above its pectoral fins. These specialized pouches secrete a bioluminescent fluid, which creates a glowing cloud in the dark. Researchers theorize this substance serves multiple purposes, such as a defense mechanism to startle and disorient potential predators, allowing the tiny shark to escape.
Another theory is that the glowing cloud acts as a lure for prey. A sudden burst of light could attract smaller fish or crustaceans, drawing them closer for an ambush. The shark’s body is also dotted with photophores, suggesting light production is important for its survival, possibly for camouflage or communication.
Natural Environment and Scarcity
The American pocket shark inhabits the deep waters of the Gulf of Mexico. The specimen was collected from a mid-water trawl at a depth of about 1,900 feet (580 meters), suggesting the species lives suspended in the water column far above the ocean bottom.
This species is extremely rare, as only one individual has ever been documented by science. This scarcity means that details about its population size, specific behaviors, and ecological role are unknown. Its life cycle, feeding habits, and interactions within the deep-sea ecosystem await future discoveries.