Olm

Proteus anguinus

Also calledČloveška ribica, 'human fish' (Slovene) · Čovječja ribica (Croatian) · Grottenolm (German) · Protée (French) · Baby dragon

A blind, pale-pink salamander that spends its whole life in the dark underground waters of the Dinaric Karst. It keeps its feathery larval gills for life, can live for more than a century and may go years without eating. A 2026 study split the olm into nine species, and iNaturalist now restricts Proteus anguinus to one of these lineages; the account here covers the olm group as a whole.

Olms are the nine species in the genus Proteus. They are aquatic salamanders, and the only exclusively cave-dwelling chordate genus found in Europe. The genus is assigned to the family Proteidae, along with Necturus. In contrast to most amphibians, this genus is entirely aquatic; eating, sleeping, and breeding underwater. Living in caves found in the Dinaric Alps, the genus is endemic to the waters that flow underground through the extensive limestone bedrock of the karst of Central and Southeastern Europe in the basin of the Soča River near Trieste, Italy, southern Slovenia, southwestern Croatia, and Bosnia and Herzegovina. Introduced populations are found near Vicenza, Italy, and Kranj, Slovenia. It was first mentioned in 1689 by the local naturalist Valvasor in his Glory of the Duchy of Carniola, who reported that, after heavy rains, the olms were washed up from the underground waters and were believed by local people to be a cave dragon's offspring. Wikipedia