New Species of Snailfish in the Atacama Trench

Snailfish are unusual animals. They have an elongated and scaleless body that is often said to resemble a tadpole in shape. The animals have a widespread distribution in the colder parts of the ocean and are found in shallow to deep water. Despite these facts, they aren't very well known or understood. Scientists have recently found three new and surprising species at a depth of 7,500 metres in the Atacama Trench.

A festive snailfish or Liparis marmoratus (a species not found in the Atacama Trench)
Kitty Mecklenburg, via Wikipedia, public domain license

Snailfish

Snailfish belong to the family Liparidae. The fish have large heads relative to their size but small eyes. They are benthic animals, which means they live on the ocean bottom. In most snailfish, the pelvic fins are modified to form an adhesive disk that attaches the body to a surface. Hadal snailfish are those that live at a depth of greater than 6,000 metres and are still somewhat mysterious. These fish have been found in the Mariana Trench as well as the Atacama one.

The Atacama Trench

The Atacama Trench is also known as the Peru-Chile Trench. It’s located in the Pacific Ocean about a hundred miles off the coast of Peru and Chile. The Nazca Plate is moving under the South American Plate in the area, a process known as subduction. The trench has a maximum depth of just over 8,000 metres and an area of around 590,000 square kilometres. In the depths of the trench the environment is dark, the water cold, and the pressure enormous, yet a surprising number of species thrive there.

The Peru-Chile or Atacama Trench (the dark line)
NOAA, via Wikipedia, public domain license

The Expedition

A recent exploration of the trench by a multinational team of scientists has revealed three new species that they believe are snailfish. The large team consisted of 40 researchers who came from a total of 17 countries. The scientists sent a remote-control lander down to the area that they wanted to explore in a trip that covered four and a half miles. One of the researchers involved in the expedition said that the walls of the vessel were made of steel almost an inch thick and the window was made of “super strong” sapphire glass. This type of glass is almost as hard as diamonds.

The lander took photos and videos and trapped specimens. It returned to the surface as a result of an acoustic signal sent from the surface. It brought one of the new fish species with it, which the researchers examined and classified as a snailfish. Some of the discoveries made by the lander are shown in the video below.

Three New Species

The new fish are being referred to as the pink, the blue, and the purple snailfish for now. Though they are different in colour, they also differ in overall appearance and are believed to be three different species. They are unusual animals because they don’t look like many of the other fish that are found in deep and dark water. They have a translucent and gelatinous appearance instead of a dark, fanged, and menacing one. Their bodies look too delicate to withstand the pressure and cold temperatures at such depths, but the fish seemed healthy and appear to be very successful in their habitat. I think the blue species is particularly interesting. Unlike the pink and purple fish, the blue animal has long, sail-like pectoral fins and a relatively long snout.

One of the purple animals entered the lander’s trap and was carried to the surface. The nine-centimetre long animal was preserved and its body CT scanned. Scans like this are important in case physical specimens of organisms and items are destroyed, as happened in the horrible fire at the National Museum of Brazil recently. Though preserved animals and a detailed scan of the animal’s external and internal features are certainly useful, they aren’t as good as observations of a living animal. Hopefully much will be learned about the new fish in their natural habitat. The remoteness of the area makes it difficult to explore, however. It also makes the trench and its unusual and specially-adapted inhabitants fascinating.

References

Three new species of snailfish discovered from the ScienceDaily news service

Finding snailfish in the deep ocean from The Conversation