During the summer of 2012, we visited Planinska Jama, which is a cave connected to the world famous Postojna Cave complex in Slovenia.
Planinksa Jama, is the place where the biggest known population of Olms occurs. They live in the huge riverine cave ecosystem of Planinska, which is connected to the famous Postojna Cave, which is classified as a World Heritage Center. The olms are extremely weird cave dwelling creatures who spend their entire life in the caves. Only after exceptional heavy rainfall and and floodings, they sometimes reach the surface and can be found outside caves. This is how the first specimen was encountered in 1751 after severe floodings. The species was then described as a fish, which explains it's original english name, the 'human fish'. As most of the exclusive cave organisms they have no pigmentation and they are blind. The genus 'proteus' only occurs in the Eastern and Central part of North America and the East-Adriatic Karst region. Proteus anguineus is only found in a small area in Italy and the karst region of Slovenia and Croatia. They only live in slow-flowing and oxygen-rich cave streams, where they spend their life in quiet and blind riverarms. They mainly feed on invertebrata, such as the water woodlouse and small crustacea, and they can survive for long periods without food.
The species is classified on the IUCN Red List as vulnerable, because of it's restricted and fragmented range and it's very specific quality-demanding habitat.
For a visit to the cave, one has to make an appointment in advance with the local guide Zvonko Samsa. Zvonko was a very nice and helpful man, who guided us through the cave and took wonderfully care of our daughters in the few places where we had to descend over the slippery rocks. After a walk of half an hour and going down in the cave, one reaches the level of the underground river and the wonderfull exploration of olm habitat starts by peddling a small rubber boat on the river. When the water level is quite low, you'll have to drag the boat quite often over slippery rocks. Luckily we had to do this only twice. The silence and the peaceful atmosphere of the cave is really wonderfull. It was a unique opportunity to be the only visitors and far away from any crowd in a spectacular cave. Which can not be said about Postojna Cave...
Under here some images of the cave.
After peddling only five minutes, we already saw our first olms, which are often quite large. The biggest specimens we saw were definitely more then 30 centimeters long! It was an amazing experience to see these weird creatures in the wild, sometimes even within hand-reach.
Most of the individuals flee quickly away from the light of the torch and expeditiously disappear into the deeper parts of the river. But several times some individuals found themselves in a large patch of shallow water and we were able to obseve them very well at close range. We saw more than hundred olms during our four hour boattrip in the cave! Under here, another picture of the odd looking 'Human Fish'. This specimen was quietly resting on a rock in shallow water and didn't seem to care at all about our presence.
From time to time, we encountered some smaller cave dwelling creatures, such as these cave wooldlice and a cave centipede. All of them are obviously also characterized by the lack of any pigmentation.
Under here: ready to go, and mission accomplished.
