Proteus anguinus or in other words Olm is considered to be a blind amphibian that is found in the subterranean waters of Dinaric Karst in the southern part of Europe. Proteus anguinus actually lives in the subterranean waters that might gush underground throughout this widespread limestone area involving waters of Soča River. Proteus anguinus is considered to be the solitary species in genre Proteus and the lone European genus of the kingdom Proteidae. At the same time, it is known as the “human fish” by local inhabitants due to its skin shade. This amphibian is very unique in the sense that its adjustment to existence of total darkness in it subversive environment. It must be kept in mind that Proteus anguinus eyes are underdeveloped thus, making it blind. While, on the other hand, identical species like hearing and smell are very developed when compared with Proteus anguinus. Olm does not have any type of pigmentation either and the overall skin is very clear without any colour or blemishes. When evaluated with other amphibians Proteus anguinus is totally aquatic and it sleeps drinks and feeds under the water only.
Olm has three toes on its limbs. This amphibian also displays special kind of neoteny, sustaining larvae features like peripheral gills into maturity and is referred to American amphibians as well. The American amphibians like muck puppy and axolotl are very similar to Proteus anguinus with respect to characteristics, sleeping, feeding and drinking traits. The body is very much similar to snakelike. On the other hand, the trunk is measured to be cylindrical, homogeneously broad and divided with frequently spaced troughs at the myomere perimeters. The tail is comparatively squat, tangentially compressed and bordered by a slender fin. The overall body is minute and skinny, with an abridged amount of digits when evaluated with other amphibians. However, the sensory organs of Proteus anguinus are considered to be extremely sharp and agile as well. The sensory organs of human fish have adapted to existence in the subterranean surrounding in the most ideal manner. Unable to utilize eyes for orientation, Proteus anguinus balances with other senses that are adequately developed when evaluated with other amphibians living on earth. It also has larval ratios like an extended, slim structure and a big, compressed skull, and is therefore competent to bear a bigger number of adequate sensory interceptors.
Proteus anguinus eyes are much retreated but have high propensity towards light. It can sense light even in complete darkness with the help from superior sensory interceptors. Photoreceptors that are present underneath the layer of skin are seldom noticeable except in few younger Olms. Larvae tend to have usual eyes but development almost immediately halts and the eyes start regressing. Chemoreceptors are very capable of visualizing very little applications of raw amalgams that may be present in water. Proteus anguinus can easily smell its prey under water with the help from photoreceptors and chemoreceptors and at the same time, it can sense the overall quality and quantity of its prey as well.