It’s official: the Earth now has a new deepest fish.
Dredged up from 26,000-feet in the Mariana Trench in 2014, the creature, Pseudoliparis swirei, is a species of snailfish, reports Craig Welch at National Geographic. Slightly pink and translucent, the small creature has evolved to survive the crushing pressures at these great depths.
Researchers have found many other species of snailfish in the deepest corners of the ocean, according to a press release. While they don’t look particularly strong, they can withstand pressures “similar to an elephant standing on your thumb.” How exactly they do this, however, is not yet fully understood.
On research trips to the trench in 2014 and 2017, researchers collected 37 specimens of the fish. In August, Japanese researchers recorded one of the snailfish at 26,830 feet—the deepest yet recorded. The researchers examined the creatures' DNA and 3D scans of bone and tissue samples, determining that the samples were indeed a new species. It is officially described in the journal Zootaxa.
So why would a fish evolve to live in the icy, dark depths of a marine trench? Co-author Thomas Linley of Newcastle University says it opens up a lot opportunities. “Snailfishes have adapted to go deeper than other fish and can live in the deep trenches. Here they are free of predators, and the funnel shape of the trench means there’s much more food,” he says in the release. “There are lots of invertebrate prey and the snailfish are the top predator. They are active and look very well-fed.”
Welch reports that it’s unlikely that there are fish that live deeper than swirei. That’s because below a certain threshold the pressure becomes so great, it destabilizes proteins. To survive at the depths in which it lives, the snailfish has developed some novel biology. “There are real limitations to life in these trenches,” first author Mackenzie Gerringer of the University of Washington tells Welch. “They have evolved adaptations to that pressure to keep their enzymes functioning and membranes moving.”
But Gerringer says there is another fish that could challenge swirei’s title. Researchers have also captured video of very delicate fish temporarily called the “ethereal snailfish” at the same depths, but no one has been able to retrieve one of the creatures.
Pseudoliparis swirei is named after Herbert Swire, an officer aboard the H.M.S. Challenger, the ship that discovered the Mariana Trench in 1875.