Scientists have been able to surface and describe as many as 39 previously unknown large animal species while using robots to explore the bottom of the central Pacific Ocean.
The bottom of the world's oceans is still poorly understood, and so are its living inhabitants. In addition to their scientific value, descriptions of abyssal fauna (i.e. areas at depths of more than three kilometres) are sometimes of conservation value. This was the case of a study published by an international team of scientists in the journal ZooKeys.
The study region was the Clarion-Clipperton Fracture Zone, located in the middle of the Pacific Ocean. Although more than three kilometres deep, it is expected to produce minerals there, including so-called nodules (shallow, rounded formations), which are polymetallic ores. They are capable of yielding nickel, copper, cobalt and other metals.
An environmental impact assessment - an assessment of local biodiversity - was therefore necessary and should be taken into account when drilling. Despite the high level of zoological interest in the Clarion-Clipperton Zone, the local fauna remains largely unexplored. Of the 55 specimens recovered, up to 39 may belong to previously undescribed species, a number that remains to be determined.
Biologists use genetic tests, including DNA barcoding, the study of small portions of the genome from which even closely related species can be distinguished.
All of the animals found and brought to the surface for DNA analysis lived at depths of more than three kilometres, including 36 at depths of more than 4,800 metres. These are the so-called benthic megafauna - benthic animals that are comparatively large (more than two centimetres). Among them there are annular worms, sessile crustaceans, arrows, various echinoderms including ophiurs and sea lilies, sponges and many others. A whole colourful gallery is assembled in the article from their photos.
"This study is important not only because we have discovered many putative new species, but also because previously megafauna specimens were studied solely from photographs. However, without DNA and the information contained in it, we simply cannot accurately identify the animals and properly count how many species are in front of us," shared Dr Guadalupe Bribiesca-Contreras, one of the authors of the study.
The scientists also noted that they came across an unexpectedly large number of animals. The abundance of millimetre-sized creatures in this area had already been described, but the megafauna simply could not be collected properly.