In 2019, marine scientists confirmed an extraordinary discovery: a new species of pocket shark, Mollisquama mississippiensis, found in the depths of the Gulf of Mexico. Measuring just 14 centimeters in length, this tiny shark possesses a remarkable ability — it glows in the dark.

The specimen was first collected in 2010 during a research expedition studying sperm whales. At the time, its significance wasn’t fully understood. It wasn’t until 2013, after detailed analysis by experts from NOAA and Tulane University, that researchers realized it represented an entirely new species. Their findings were later published in the journal Zootaxa.

What makes this shark so extraordinary is its built-in bioluminescent system. Behind its gills, it has pocket-like glands that release a glowing fluid, possibly to attract prey or confuse predators in the deep, pitch-black ocean. Its skin is also covered with tiny light-producing organs called photophores, giving it an ethereal glow.

High-tech imaging techniques, including CT scans and X-rays, confirmed its unique anatomy. Compared with related species, Mollisquama mississippiensis has fewer vertebrae, distinctive teeth, and a jaw structure that may act as a pressure sensor, helping it navigate the crushing depths of its habitat.

This discovery represents only the third known shark species capable of squirting luminous fluid, joining the taillight shark and another rare Pacific pocket shark. For scientists, finding Mollisquama mississippiensis after decades without new sightings of pocket sharks is a striking reminder that the oceans remain largely unexplored, harboring countless secrets in their darkest depths.