A bizarre fish, new to science, has been discovered in the deepest waters on the planet, setting a new record for fish depth by living 26,715 feet below the ocean surface.
Filmed swimming in the Mariana Trench in the Pacific Ocean -- the deepest spot on Earth -- it is thought to be a previously unknown species of snailfish, which are inhabitants of extreme depths.
However, the new fish, discovered during an expedition led by researchers from the University of Hawaii, is not shaped like other known varieties of snailfish, with broad, wing-like fins and an eel-like tail with which it glides smoothly through the water.
"We think it is a snailfish, but it's so weird-looking; it's up in the air in terms of what it is," says expedition member Alan Jamieson from Oceanlab at the University of Aberdeen in Scotland.
"It is unbelievably fragile, and when it swims, it looks like it has wet tissue paper floating behind it.
"And it has a weird snout -- it looks like a cartoon dog snout," he says.
The fish was observed at a depth scientists believe might be the limit for how deep fish can survive.
The intense pressure at those depths can hinder nerves and muscles and even warp and alter proteins linked to the operations of enzymes necessary for life, experts explain.
Deep-sea species of fish survive because they possess high levels of the chemical trimethylamine oxide (TMAO), which can allow proteins to maintain their proper shape under increasing pressure.
However, recent research by Jamieson suggests there's an absolute depth limit -- 26,900 feet -- below which fish could not hold sufficient TMAO in their cells to survive.
That suggests the newly discovered snailfish -- if that's what it is -- may go into the books as the permanent record holder.
Without caching one and returning it to the surface there's no way to confirm it's an entirely new species, the researchers acknowledge, but they remain confidant it's nothing previously seen or known.
Although the fish were filmed at the bottom of the Mariana Trench using unmanned research vehicles in the recent expedition, human have visited those depths.
The first time was in 1960 when a U.S. Navy officer and a Swiss oceanographer reached the trench's bottom in a submersible named the Trieste.
Then in 2012 film director James Cameron, in a solo descent, reach the Mariana Trench seafloor in a diving craft named Deepsea Challenger.