The proteus is a cave-dwelling salamander that lives in the underground rivers of Slovenia and northern Italy. Like many cave-dwelling species, it has a very limited range. They are “prisoners of the underground environment,” meaning that they cannot live outside of caves and hence are unable to colonize distant habitats.
During its tours, Clamouse presents 4 specimens on loan from the Experimental Ecology Station of the Moulis (Ariège) National Research Centre.
This is the only cave-dwelling vertebrate in Europe and one of the world’s largest. Other vertebrates (amphibians and especially fish) exist in the tropics. It is also one of the first cave-dwelling animals ever described. Its common name, holm, means little dragon. They were first discovered in an intermittent cave stream (where the water flow varies regularly) and people thought this was due to a dragon turning around.
During floods, the proteus is sometimes forced out of the cave, and its “larval” appearance made it appear to be a small dragon.
The largest individuals grow to about 30 centimetres. At Moulis, some specimens have lived more than 60 years. Their life expectancy is close to that of humans.

Its body is elongated (hence its Latin name anguinus) and its feet are small. It has no skin pigmentation: it is depigmented.

The blood circulating under its skin gives it a pink fleshy colour. In back of its head, to each side, it has red featherlike gills that allow it to breathe oxygen dissolved in the water.

It is anophthalmic (has no eyes). In its early larval stages, a rudimentary eye develops slowly, but then development halts and the outline of the eye then regresses.

If a proteus is exposed to light, its eye does not develop: the regression is irreversible. But its body will take on a darker hue.

This is a neotenic animal, which means that in the adult (able to reproduce) state it retains larval features (external gills, laterally flattened tail adapted for swimming), reduced limbs, little ossification, non-functioning rudimentary lungs. It undergoes incomplete metamorphoses. The last one occurs when it is 11 years old. Its life cycle (like that of all cave-dwelling animals) is very long.

Depigmentation and anopthalmia are its most significant adaptations to the underground environment. We should also mention its ability to go without food for a long time (nutrient-poor underground environment), and its reduced metabolism (tires quickly, longs a long time, very developed senses of smell and touch). We sometimes speak of “old-people’s metabolisms” in regard to cave-dwelling animals. It lays a small number of eggs (about 30) which are large compared to other similar species that are epigeal (surface-dwelling). It has no predators and therefore needs a smaller number of descendants.

In its natural environment, it is at the top of the food chain. It is the “tiger” of the underground. It feeds mainly on cave-dwelling crustaceans.