How we found a beautiful new species of snailfish deep beneath the sea. Researchers discovered these ethereal purple specimens four-and-a-half miles down.

Pedro_P

Inside a snailfish.
Newcastle University / Natural History Museum, London, Author provided
▼ From an unmanned submersible, protected by a casing of stainless steel almost an inch thick and a window made from super strong sapphire crystal, we can observe the life that thrives at our planet’s most extreme and darkest depths. Thanks to technology and sheer material strength, we can temporarily trespass into this high pressure environment. But in stark contrast to the robust deep sea imaging equipment we rely on, the creatures our camera records look extremely fragile.
Four-and-a-half miles beneath our research vessel, which was floating on the surface of the Pacific Ocean, we captured footage of several previously undiscovered species of hadal snailfish. With delicate fins and transparent, gelatinous bodies, they are some of this environment’s most enigmatic  inhabitants, fish that—at first glance—look like they should be incapable of surviving under such enormous pressures. And yet, it appears they are thriving in this strange world.
In spring, a team of 40 scientists from 17 different nations conducted an expedition to the Atacama Trench, which runs along the west coast of South America. We were there to find a particular snailfish.

The Atacama trench is the dark blue line off the coast of Chile and Peru.
NOAA
On a previous expedition, our principal investigator (Alan Jamieson) had photographed a  snailfish with long, wing-like finsat a depth of 7,000 metres. Only one species, Notoliparis  antonbruuniwas known to inhabit this area at such a depth. It had been described from a single specimen, so badly damaged that we are not able to use it to identify our images of living animals. We wanted to find this elusive winged snailfish again to learn more about it and observe it in its natural habitat.
These hadal snailfish tend to live at depths between 7,000 and 8,200 metres (“hadal” simply means anywhere below 6,000 metres), but their apparent rarity is perhaps misunderstood. Because of their extreme habitat (at least for humans), they are difficult to observe rather than actually “rare” as we know it. And with the right equipment and opportunity, we were confident, after ten years of study, that we knew where and how to find them.
The Atacama Trench is part of the Peru-Chile subduction zone, a large 590,000 square kilometre area where one tectonic plate is being forced under another and the ocean floor quickly plunges to more than 8,000 metres. Its volume is almost the same as the neighbouring Andes mountain range, which the tectonic subduction zone also creates, and exploring it is no easy feat.

Deep dive.
Newcastle University, Author provided
A trio of snailfish (▪ ▪ ▪)

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