There's no doubt that the deep ocean holds many secrets, and in good news for the aquatically curious marine scientists are getting better and better at bringing them to the surface. A new exploration to the Atacama Trench off South America's west coast has shed new light on one of the Earth's deepest places, including video evidence of what appears to be three brand new species of marine life.

The expedition was carried out using a pair of lander systems fitted with HD cameras and traps. Built to withstand the pressure at depths of up to 11,000 m (36,000 ft), these landers are simply dropped off the side of a boat and left to sink to the ocean floor. To retrieve them, scientists send down an acoustic signal that releases a set of attached weights from the lander and frees it to float to the surface.

The international team of scientists working on the project did this 27 different times over the Atacama Trench, including deployments to the deepest point, called Richard's Deep, of more than 8,000 m (26,000 ft). Throughout they gathered more than 100 hours of video and 11,000 photographs.

Captured within was imagery was rare footage of long-legged isopods – crustaceans around the size of a human hand that swim upside down and are rarely sighted in their natural habitat. Rarer still was footage of what scientists believe to be three new species of snailfish, which for now they have dubbed the pink, blue and purple Atacama Snailfish.

Other recent research expeditions of this nature have also turned up new types of snailfish, such as the Mariana snailfish found residing in the Mariana Trench, the deepest known part of the ocean with a maximum depth of 36,000 ft (11,000 m). One jaunt captured these creatures swimming around at a record-breaking depth of 26,830 ft (8,178 m).

The snailfish spotted in the Atacama Trench aren't quite that intrepid, but were captured feeding and floating about 7,500 m (24,000 ft) below the surface. While the idea of deep sea animals might conjure up images of nightmarish creatures with sharp teeth and death in their eyes, the snailfish are a small nondescript species without scales. They do, however, seem perfectly evolved to live at such depths.

"There is something about the snailfish that allows them to adapt to living very deep," says Newcastle University's Dr Thomas Linley, member of the research team. "Beyond the reach of other fish they are free of competitors and predators. As the footage clearly shows, there are lots of invertebrate prey down there and the snailfish are the top predator, they seem to be quite active and look very well-fed."

The team did manage to capture one of the snailfish for further analysis on dry land, though it died due to the warmer temperatures and lower pressure well before it reached the surface.

"Their gelatinous structure means they are perfectly adapted to living at extreme pressure and in fact the hardest structures in their bodies are the bones in their inner ear which give them balance and their teeth," says Linley. "Without the extreme pressure and cold to support their bodies they are extremely fragile and melt rapidly when brought to the surface."

The team presented its research at the 2018 Challenger Conference for Marine Science this week. The video below shows the newly discovered species doing its thing.

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