Mariana Snailfish: Deepest-ever Fish Discovered at 26,000 Feet under the Sea

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A CT scan reveals this Mariana snailfish ate a small crustacean for lunch. Adam Summers/University of Washington

The deepest-ever species of fish has been recovered from the Mariana Trench. Thriving at 26,200 feet below sea level, the small, slimy and translucent fish have somehow adapted to one of the harshest places in the ocean.

Earlier this year, a Japanese team filmed suspected snailfish swimming as deep 26,830 feet, but did not recover any samples. 

In a series of dives in 2014 and 2017, a small team of researchers from the U.S. and U.K. dropped special traps into the depths of the Mariana Trench in the Pacific Ocean in order to catch the elusive creature. This trench shoots through the ocean floor near Guam and is home to the deepest point in Earth's seas.

Taking up to four hours to reach the bottom of the trench, scientists left the traps for up to 24 hours. The traps—equipped with specialist cameras—emerged with incredible footage of the new species, named the Mariana snailfish, as well as 37 other fish over the course of the study. Their results were published in the journal Zootaxa.

Deepest fish ever recovered

“This is the deepest fish that’s been collected from the ocean floor, and we’re very excited to have an official name,” said lead author Mackenzie Gerringer, a postdoctoral researcher at the University of Washington’s Friday Harbor Laboratories, in a press release. “They don’t look very robust or strong for living in such an extreme environment, but they are extremely successful.”

First located in 2014, researchers have been investigating the snailfish ever since. The small, slimy creatures have adapted to thrive under the intense pressure of the Mariana Trench. At its deepest—more than 36,000 feet—the pressure is approximately 1,000 times the standard atmospheric pressure of water. This would be like an elephant standing on your thumb. 

11_29_Deepest fish_02 The new species is small and transparent. Mackenzie Gerringer/University of Washington

Despite these harsh conditions, living at the bottom of the sea can have its benefits. “Here they are free of predators, and the funnel shape of the trench means there’s much more food,” explains study co-author Thomas Linley of Newcastle University. “There are lots of invertebrate prey and the snailfish are the top predator. They are active and look very well-fed.”

State-of-the-art 3-D model of the new species

Scientists further analyzed the fish samples using state-of-the-art CT imaging, which enabled them to create a 3-D model of the species. Researchers were able to confirm the Mariana snailfish—or rather, Pseudoliparis swirei—as a distinct, new species.

As sea exploration technology improves, more and more deep-sea creatures are being brought to the surface. Last year, two new species of glow-in-the-dark fish were discovered in the ocean’s “Twilight zone," which lies between 1,300 and 3,000 feet below sea level.

“There are a lot of surprises waiting,” Gerringer said. “It’s amazing to see what lives there. We think of it as a harsh environment because it’s extreme for us, but there’s a whole group of organisms that are very happy down there."

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