The Mariana Trench is known as the deepest point in our planet’s waters, spanning through the west Pacific Ocean’s floor near Guam. While only a few types of marine species can exist in these extremely deep waters, researchers have just discovered one specific species of fish that does – the Mariana snailfish. This creature is now believed to be the world’s deepest-living fish species ever spotted, with a team of scientists having just confirmed sightings from over 26,000 feet below the surface.
Scientists have known for some time that creatures such as jellyfish, sea cucumbers, and one-celled organisms known as foraminifera can be found in the Mariana Trench. But the Mariana snailfish also happens to be among the animals that make their home in these depths, and as Quartz noted, the two-inch-long, translucent fish was officially declared a new species on Tuesday, and given the scientific name pseudoliparis swirei.
Because the waters of the Mariana Trench are too deep for human divers to swim in, researchers from the United States and United Kingdom used cameras and traps to track the movements of the mysterious fish, and catch samples of it to prove its existence. According to Newsweek, this was a process that covered multiple dives in 2014 and 2017, and it took up to four hours for the traps to reach the trench’s bottom, with each trap left for up to a day. The traps came with special cameras that returned visual proof of 38 fish over this series of dives, but the Mariana snailfish stood out for being the deepest-living fish ever sighted.
While humans may think of the Mariana Trench as an unfriendly environment due to its depths, University of Washington marine biologist and lead researcher Mackenzie Gerringer commented that the Mariana snailfish is one of several organisms “that are very happy” with their environment.
“They don’t look very robust or strong for living in such an extreme environment, but they are extremely successful,” she observed.
Although the researchers were able to gather a sample Mariana snailfish swimming at least 26,600 feet below the surface, there’s a chance that the creature can exist at slightly deeper parts of the Mariana trench. Earlier this year, a separate team of Japanese researchers reported a snailfish sighting, filming the creature swimming at depths of 26,830 feet (8,178 meters), according a press release from the Japan Agency for Marine-Earth Science and Technology. But as Newsweek pointed out, the Japanese team was not able to bring back any samples.
Regardless of the exact depths in which these fish can be found, they deal with extreme water pressure on a daily basis, with the University of Washington describing the pressure as akin to “an elephant standing on your thumb” in an press release published in EurekAlert. But there are some positive tradeoffs to living so close to the bottom of the sea, as Newcastle University researcher and study co-author Thomas Linley of Newcastle University explained. He said that the Mariana Trench’s funnel shape allows for a steadier, more abundant supply of food, with its depths also keeping predators out.
“There are lots of invertebrate prey and the snailfish are the top predator. They are active and look very well-fed.”
As there are up to 400 different species of snailfish that exist in different depths and come in lengths ranging from two to 30 inches, the Mariana snailfish comes with its share of distinguishing features, including its unique combination of dorsal and anal fins, Quartz wrote. The fish was identified as a new species after the researchers took its measurements and analyzed its DNA samples, eggs gathered from females of the species, and its skeletal and tissue structure.