The olm - Baredine cave

The olm (Proteus Anguinus Laurenti) is an endemic amphibian in the family Hypophthalmichthys and the only remaining specimen of the family. It is an aquatic salamander (Amphibia in the Caudata / Urodela family).

Distribution and habitat

It is the sole indigenous European (stigobiotic) amphibian, at the same time being the world’s largest truly subterranean animal. It resides in the underground waters of a wider area of the Dinaric Karst, in parts of Italy, Slovenia, Croatia, Bosnia and Herzegovina. It is only the Dinaric parts of Croatia that boast 68 locations that have recorded the presence of the olm at least during one period.

Specimen description

it has a longish, soft, eel like body. Adult olms usually reach a length of 20 to 25 centimetres, males being in general a bit shorter than females. It is white coloured (pigmentation deficiency) with yellowish and pinkish tints from the surface capillaries. The olm is also called ‘’human fish’’ because of its skin resemblance to the human skin. Its eyes are completely regressed and covered by skin due to a life in permanent underground darkness. The eyes are still visible among the younger olms, though. Its flattened tail, which is shorter than the rest of the body, has a leather fin. The olm has tiny limbs with three poorly developed front toes, while its hind feet have two toes. Its respiratory system includes gills (retaining the three external fluffy gills on either side of the head into adulthood) and skin, along with lungs as secondary organs at conditions when oxygen levels are very low.

Evolutionary peculiarity

Unlike most of the other amphibian specimen, the olm never completes the total transformation, thus retaining the morphological characteristics of larvae even into adulthood. Such occurrence is called NEOTENY. Morphological features of neotenic animals are three pairs of big, forked red gills, a short and narrow tail fin, and shrunken eyes.


The olm feeds on underwater crabs, maggot like worms, insect larvae (mostly mayflies and plectopera) and molluscs. These animals live either in the underground or they get there from the outside (brought in by water or they just fall down into caves). It is scientifically proved that the olm can, under extraordinary conditions, live up to 1 year without any food.


Olms are sexually reproducing through eggs. They reach their sexual maturity around the age of 15. If fertilization happens, females lay their eggs 2 or 3 days after it occurs. They can lay a total of 70 eggs each.

Old age

The olm is the amphibian with the longest lifespan. It is assumed that they can live up to 100 years. The reasons for such longevity are their reduced activity, slow metabolism and the inexistence of any enemies in their habitat.

Legend has it

There has been a belief spread around these areas that some caves are homes to dragons that control the amounts of water surfacing the caves. Dragons would occasionally dry up the springs and once they let the water back, their dragon offspring used to emerge to the surface as well. People would then find these, not knowing they were olms, but believing those were little dragons.

The istrian olm

It was first seen in Istria some 100 years ago, to be discovered later on more localities. It is believed that there is a several million year divide between the Istrian olm population and its neighbouring populations of the Dinaric Karst area. It obviously differs from those by its specific morphological features, while an important genetic difference has been proved in recent times. Therefore, it has been scientifically denominated as a new subspecies under the name of the Istrian olm. It was first found in the underground waters of the Poreč area in 1975 by local speleologists (members of the Speleological Society Proteus). Thanks to this discovery, today you can meet the Istrian olm during your visit to the tourist purposes modified Baredine cave.