The human fish – also known as the proteus or olm – is a tailed amphibian the colour of human skin which grows to a length of 30 centimetres. The human fish on view in the part of the cave open to tourists are slowly becoming darker in colour because of their exposure to the light. They breathe like fish – through gills – but they also have atrophied lungs and eyes. The human fish is adapted to life in the underworld and its oxygen consumption is extremely low. It reproduces oviparously and does not undergo metamorphosis like other amphibians. Valvasor reported on the human fish 300 years ago when he was shown a specimen of a 'baby dragon'. It was later classified as one of the stages of development of the lizard, and it was not until the beginning of the 19th century that it was confirmed as a separate species.
