This cave amphibian, whose skin is totally depigmented, measures between 15 and 25 centimetres. It is blind, but can feel the vibrations of water, and can live up to 100 years old.
The Proteus, which lives mainly in the waters of the karst caves of the Dinaric Alps crossing Slovenia, Croatia and Bosnia-Herzegovina, is the only strictly cavernous vertebrate in Europe and is therefore a protected species.
The caves where the underground laboratory of Moulis is installed, constitutes one of the rare experimental installations in the world dedicated to this research.
Indeed, aquariums and cement ponds fed by the waters of the underground river are installed. More than thirty Proteus are being studied on (years of birth and death, maturity, sexual maturity, reproduction rate, number of eggs) to understand the biological mechanisms of adaptation of these species to their environment, unchanged for millions of years.