Proteus Anguinus


Scientific name: Proteus anguinus LAURENTI 1768
Systematics: Phylum Chordata
Class Amphibia
Order Urodela
Familiy Proteidae
Genus Proteus LAURENTI, 1768
Species Proteus anguinus

Proteus anguinus, Brehms Tierleben, 1890, p 838. Public Domain.
Proteus anguinus, Joseph Nicolaus Laurenti (1768): Specimen Medicum Exhibens Synopsin Reptilium Emendatam Cum Experimentis Circa Venena Et Antidota Reptilium Austriacorum, p 225. Public Domain.
The proteus or olm.
Photographer: Arne Hodalic
© Slovenian Government Public Relations and Media Office, with kind permission.
Proteus anguinus in ShowcavePlaninska Jama in Slovenia.
© Helmut Schlierf, Zirndorf.
Proteus anguinus in ShowcavePostojnska Jama, Slovenia. Public Domain.

Proteus anguinus is a true troglobiont. It is an amphibian salamander, living only in the Dinaric Karst, the karst areas along the Mediterranean Sea from Trieste in Italy to Herzegovina. It can only be found in this region, it is a so-called endemic species. Additional occurrences, in the Harz in Germany, in Moulis in France or in Grotte Oliero in Italy go back on human intervention. During several hundred years of research numerous specimen were relocated for scientific purposes.

The Proteus in the Dinaric karst is the remainder of a Tertiary family of amphibians, it is today nearly extinct with only six remaining genuses worldwide. Proteus was known by Charles Darwin, who writes about cave animals in chapter 5 of his book The Origin of Species: WorldEffects of Use and Disuse. He calls them "wrecks of ancient life".

Proteus looks like a salamander, but because of the pink skin and the small arms and legs, it looks also a little bit like a small human. This is the reason, why it is also called Human Fish, though it is neither. Other names of Proteus anguinus are Olm and White Salamander.

The Olm has no eyes and no pigments in the skin, if grown in the darkness of a cave. A particularly interesting fact is that olms develop both eyes and skin pigments when they grow up in the light. This ability has obviously been preserved from an earlier stage of evolution. But then the eyes are not complete, some important parts of the optic nerve are missing, and so these olms have eyes but are still blind.

Due to their lightless life, olms are completely pigmentless, appearing pale, almost translucent. They reach a length of around 17 to 26 cm and weigh 20 g. They also have no eyes, which would be completely pointless in the dark. The olm breathes with gills behind its head, at the left and right side of the body. The gills are outside the body and are transparent, they look reddish because of the blood flowing through. But it is an amphibian animal and has also lungs to breathe on land.

Olms are said to become older than 100 years. This is not proven until now, as it is very difficult to examine them in their natural environment. They are able to go without food for up to six years. One reason is the low temperature of the cave water, where the whole metabolism is low.

Since the 19th century, scientific institutions in Europe have examined Proteus anguinus. Specimens were relocated to other caves to test which influences the slightly different environment has. Most of the relocations were successful, and where both genders were released, the population stabilized. One example is the spring of Oliero, where they seem to have established. During the mit 20th century, the socialist Slovenian government gave living specimens of olms to several institutions in the world. But they exported only male animals to prevent reproduction.

Hermannshöhle Han-sur-Lesse Aggtelek Grotte Oliero Kent's Cavern Kent's Cavern Moulis
The natural habitat of the Proteus anguinus is marked in dark red.
The bright red dots show locations where specimen were relocated to for scientific purposes.