Below is an article published by Basque Research:

Four new species of arthropods, identified at the University of Navarra, have been found in the deepest cave in the world, at a depth of 2,191 metres.

A Spanish-Russian expedition has identified four new species of animals in a cave in the region of Abkhazia, near the Black Sea. It is the deepest in the world, at 2,191 metres. Two of these species were found at the deepest point.

The team formed by researchers Sofía Reboleira, from the University of Aveiro (Portugal), Alberto Sendra, from the Valencia Museum of Natural Science -jointly in charge of the expedition -; and University of Navarre zoologists, Rafael Jordana and Enrique Baquero, who identified and described the new species.

All the new species belong to collembola (springtails), a group of numerous arthropods which are close to insects, arachnids and crustaceans. They are characterised by having an external skeleton and appendixes (articulated legs, antennae, etc.), besides a special organ for springing called a furca. Due to their cave way of life, the four new species possess specific characteristics for surviving in extreme subterranean conditions, such as the total absence of light and scarce availability of food resources.

"As a response to these conditions, none of the animals have eyes and also lack pigmentation (colour). Moreover, one of the species has developed a chemoreceptor - a kind of chemical parabolic antenna – that enables it to move in such a complicated environment”, explained Enrique Baquero, zoologist and lecturer in the Masters course in Biodiversity, Landscape and Sustainable Development at the University of Navarra, and one of the authors of the research.

The scientific research describing the findings has just been published in TAR (Terrestrial Arthropod Reviews), from the Brill publishing company. According to Enrique Baquero, the presence of these species in such a rough environment can be explained by the presence of organic material. “They feed off fungi that grow on organic material, contributing to their decomposition and taking part in the network of stable communities of arthropods existing in the caves”.

Each of the species, the individuals of which measure between 1 and 4 millimetres, was found at a specific depth. Their names are Anurida stereoodorata, Deuteraphorura kruberaensis, Schaefferia profundísima and Plutomurus ortobalaganensis., the last two found at the greatest depth of 1,980 metres below the surface.

The Krubera-Voronya cave is the only one worldwide over two kilometres deep. Despite numerous expeditions and attempts, this is the first to describe its fauna.