New Species of Translucent, Gelatinous Fish Discovered in the Deep Sea

Outfitted with glossy, swishing tails and fan-like fins, snailfish now come in delightful shades of pink, purple, and blue. But without the pressures of the deep sea to support them, their fragile, boneless bodies melt when they crest the surface of the sea.

This week, scientists from Newcastle University report the discovery of three new species of snailfish nearly 25,000 feet below the surface of the sea. The efforts were borne out of a collaboration between 40 scientists from 17 different nations trawling the waters of the Atacama Trench, a cavernous, rocky gash near the South American coast of the Pacific Ocean.

The trench is home to pressures approximately 750 times what we feel at sea level, and frigid temperatures just a hair above freezing.* But the newly discovered snailfish are perfectly content to swim these hellish waters, due in part to their gelatinous bodies, which are almost entirely free of bones, save for the little structures in their inner ears that help with balance.

Snailfish look nothing like you’d expect: With their bulbous heads and tapered, ribbon-like bodies, these marine fishes more resemble frowning tadpoles than their slow-moving, shell-shackled namesakes on land. But over 100 species of snailfish exist, and scientists estimate many more remain undescribed, especially at the ocean’s greatest depths.

“Something about the snailfish… allows them to adapt to living very deep,” explains Newcastle University’s Thomas Linley, one of the scientists leading the expedition, in a press release. Whatever the adaptations are, they serve the snailfish well: Even though they each clock in at less than a foot long, according to Linley, at such extreme depths, they’re “top predators” and “look very well-fed.”

One of the new snailfish specimen was even ensnared by the researchers’ traps, which are equipped with tasty bait to lure fish and video cameras that acquired over 100 hours of footage of ultra-deep sea life. Tragically, when brought to the surface, snailfish bodies “melt rapidly” from the lack of pressure, but the researchers took great pains to preserve their single specimen, which is now being studied.

The three new species will be bequeathed true scientific names once the findings are published in a scientific journal, David Grossman reports for Popular Mechanics. Until then, they have been dubbed the pink, purple, and blue Atacama snailfish.

Although ocean waters blanket nearly three-quarters of Earth’s surface, scientists estimate that more than 80 percent of the underwater realm of life remains unexplored. More than 2,000 new marine species are described with each passing year.

As Maddie Stone at Earther reports, most expeditions into the abyss return some previously unseen life form. But even Linley marveled at “[finding] three species so clearly different at the same time.”

*Editor’s Note, September 12, 2018: A previous version of this article incorrectly stated that pressure in the trench was approximately 2,500 times what we feel at sea level, when, in fact it is about 750 times. The story has been edited to correct that fact.

Katherine J. Wu | | READ MORE

Katherine J. Wu is a Boston-based science journalist and Story Collider senior producer whose work has appeared in National Geographic, Undark magazine, Popular Science and more. She holds a Ph.D. in Microbiology and Immunobiology from Harvard University, and was Smithsonian magazine's 2018 AAAS Mass Media Fellow.