Behold the Deepest Fish Ever Filmed

Scientists have taken video footage of a fish more than five miles below sea level. Swimming 8,336 meters beneath the surface, the animal is now the deepest fish ever captured on film.

The creature is a juvenile snailfish of an unknown species from the genus Pseudoliparis, according to a statement from the University of Western Australia. Cameras recorded the fish in the Izu-Ogasawara Trench, located in the western Pacific Ocean, south of Japan.

Shortly after, the team set another record—they picked up the deepest fish ever caught. At a depth of 8,022 meters, a hair under five miles below sea level, they captured two snailfish. Until then, no fish had been caught below 8,000 meters.

The footage was captured as part of a ten-year project to study the world’s deepest fish populations, located in the Ryukyu, Izu-Ogasawara and Japan trenches. Scientists from the University of Western Australia and the Tokyo University of Marine Science and Technology contributed to capturing the video.

Originally recorded in September, the footage was released this week and depicts a lone snailfish swimming at the record-setting depth, as well as several fish feeding at bait in slightly shallower waters.

“What is significant is that it shows how far a particular type of fish will descend in the ocean,” Alan Jamieson, a deep-sea scientist and explorer at the University of Western Australia who led the expedition, tells CNN’s Chris Lau.

Finding the world's deepest fish

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To collect the video, the researchers used an autonomous camera system dropped over the side of a ship, according to BBC News’ Jonathan Amos. They also attached bait to the cameras to entice fish to swim nearby.

“The Japanese trenches were incredible places to explore; they are so rich in life, even all the way at the bottom,” Jamieson tells Reuters.

Snailfish are long, gelatinous, tadpole-shaped fish with scaleless skin, tiny eyes and translucent bodies. These suction feeders eat small crustaceans in the North Atlantic, North Pacific, Arctic and Antarctic seas and reside in both shore waters and the deep.

The animals have adapted to survive at great depths, where the pressure is 800 times higher than it is at the ocean’s surface. To cope, snailfish lack a swim bladder, a gas-filled organ many other fish have to control their buoyancy, writes BBC News.

“Trying to maintain a gas cavity is very difficult at high pressure,” Jamieson tells the Guardian’s Donna Lu.

Jamieson and colleagues previously hypothesized that fish would be unable to survive at depths below 8,200 to 8,400 meters, per the Guardian. The concentration of osmolyte, a fluid in fish cells that helps them survive extreme pressures, maxes out at those depths, he tells the publication.

So, it’s unlikely the scientists will find fish at much greater depths than the recently recorded juvenile snailfish. “If this record is broken, it would only be by minute increments, potentially by just a few meters,” Jamieson tells BBC News.

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.