A bizarre, ghostly fish with wing-like fins has been spotted gracefully gliding through the ocean at depths of 8,143 meters below the surface, smashing the world record for the deepest documented living fish. What’s more, the animal, which researchers believe is likely a type of snailfish, could be a species previously unknown to science.
The discovery was made during a month-long international expedition to the Mariana Trench. Located in the western Pacific Ocean near the Mariana Islands, the trench is the deepest part of our oceans, reaching staggering depths of almost 11 kilometers. The voyage, called the Hadal Ecosystem Studies (HADES) expedition, was conducted from the Schmidt Ocean Institute’s research vessel, Falkor, under the direction of a duo of scientists from the University of Hawaii.
The team deployed five deep-sea vehicles, called landers, at more than 90 different locations along the trench, ranging between depths of 5,000 meters (16,404 ft) and 10,600 meters (34,777 ft). The researchers chose this graduated approach, rather than honing in on just the deepest parts, because it helps us understand the relationships between life and geologic processes.
“Many studies have rushed to the bottom of the trench, but from an ecological view that is very limiting,” co-chief scientist Dr. Jeff Drazen explains in a news release. “It’s like trying to understand a mountain ecosystem by only looking at its summit.”
Prior to this expedition, the world record holder for the deepest living fish was a species of snailfish, the Hadal Snailfish Pseudoliparis amblystomopsis. Seventeen members of this sociable species were filmed a few years back in the Japan Trench, also in the Pacific Ocean, at depths of 7,700 meters (25,262 ft). More than 360 different species of the tadpole-like, gelatinous snailfish have been described, and each deep trench investigated so far seems to host its own species.
Thanks to some irresistibly stinky bait strategically placed on the camera-laden landers, scientists now know that these fish live much deeper than that. They managed to spot a weird-looking suspect snailfish at 8,143 meters, which sported the typical tapered body and eel-like tail characteristic of this family. However, researchers believe it could be a previously unknown species because it didn’t seem to resemble any other snailfish on record.
“It is unbelievably fragile, and when it swims, it looks like it has wet tissue paper floating behind it,” said Dr. Alan Jamieson from Oceanlab. “And it has a weird snout—it looks like a cartoon dog snout.” But without a specimen to examine at the surface, the researchers cannot be certain that it is a new species.
Although life always seems to find a way, this could be the deepest that scientists discover living fish. That’s because it dwells close to the depth limit that scientists believe fish can survive—8,200 meters—which is determined by the organism’s level of a chemical called trimethylamine oxide (TMAO). TMAO prevents proteins from becoming distorted as a result of the intense pressure experienced in the deep ocean, but there is only so much of this molecule that cells can cope with.