World's Deepest-Living Fish Found Five Miles Beneath the Surface

By Ryan F. Mandelbaum on at

The oceans’s deepest point is Challenger Deep, a chasm  almost 11,000 metres (36,200 feet) below the surface. Few fish species can stand this dark, hostile environment—but scientists have identified one that flourishes.

Image: Mackenzie Gerringer/University of Washington

Meet the Mariana snailfish or Pseudoliparis swirei, the deepest fish species collected from the ocean floor. Scientists netted samples from 7,966 metres (26,135 feet) at the deepest, but their video spotted some as deep as 8,098 metres (26,569 feet)—and recently, a Japanese team spotted one at 8,178 metres (26,830 feet). That’s real deep.

There’s been talk about a new species living this deep since a 2014 visit to the trench. But now, this slimy boogerboy has an official name.

The fish has a fleshy coloured body with transparent skin through which its organs and muscles are visible. Some bigger ones have dark spots on their heads. Scientists at the University of Hawaii, Newcastle University and the University of Washington spotted it on several research trips from 2014 to 2017, pulling up 37 specimens on a mission using the R/V Falkor research vessel. The fish is named for Herbert Swire, HMS Challenger officer credited with discovering the Mariana Trench.

The fish may look fairly foetal, but they’re the top predator down in the trench where there’s little competition to feed on the invertebrates, according to a University of Washington statement. They team published the paper announcing the discovery yesterday in the journal Zootaxa.

It’s not a surprise that this slippery snailfish lives so deep—snailfish do occasionally get caught on film down there including similar species like Pseudoliparis amblystomopsis. DNA analysis determined that P. swirei was a different species all along.

Nice to meet you, Mariana snailfish. Have fun down there. [Zootaxa via the University of Washington]


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