Its body is snakelike and can grow up to thirty and, exceptionally, forty centimetres in length. The trunk is cylindrical, of uniform thickness, and segmented, with regularly spaced furrows. The tail is relatively short, laterally flattened, and surrounded by a thin fin. The limbs are small and thin: the front legs have three digits, and the rear have two. Its body is covered by a thin layer of skin, which contains no melanin, and very little of the pigment riboflavin, making it yellowish-white or pink in colour. The internal organs can be seen shining through the abdomen. The resemblance in colour to human skin is the reason that Proteus is known as the ‘human fish’ in some languages (including Slovene). 

These small creatures, living in subterranean lakes and ponds, are capable of sensing extremely low concentrations of organic compounds. They are better at sensing both the quantity and quality of prey by smell than related amphibians. A new type of sensory organ has been discovered on the head of the olm: these animals can sense weak electric fields emanating from living creatures and other sources. Thus, the Proteus gathers information in order to communicate, orient itself and sense prey.

You will agree that the olm has a special place in our country’s natural heritage. Ever since it was first discovered, it has delighted both scientists, and the casual but curious visitor.