Proteus anguinus

Olm, Blind cave salamander, Grottenolm, hulepadde, koopaolm, Proteo, Protée anguillard, hulesalamander, odmieniec jaskiniowy, olmi, covecija ribica, cloveska ribica.


Elongate and slender salamander with small, thin extremities. The front legs bear 3, the rear legs 2 toes. The flattened tail is markedly shorter than the body. The head is elongated with a rounded snout. The eyes are poorly developed and covered by skin in the nominate subspecies. There are three pink external gills on each side of the head. The skin is whitish with a pink hue due to the skin capillaries. The translucent skin also shows the contours of the internal organs, making it easy to determine the sex of adults. Juveniles sometimes show a faded spotting. Dark pigmentation can be induced by exposure to light. This shows that these animals do not display albinism, as commonly thought, because they still possess the ability to produce melanin. The subspecies P. anguinus parkelj has a permanent dark pigmentation of the skin, and functional eyes. It also has a shorter head than P. a. anguinus. The average total length lies between 23-25cm Males are somewhat smaller than females. Other sexual characteristics are the shape and size of the cloaca during breeding activity, the males having a larger and more elongated swollen cloaca than the females. 

Country distribution from AmphibiaWeb's database: Slovenia, Italy, France, Croatia, Bosnia and Herzegovina. European Distribution. From Gasc, J.P., et al. Atlas of Amphibians and Reptiles in Europe. 

Distribution and Habitat:

Country distribution from AmphibiaWeb's database: Slovenia, Italy, France, Croatia, Bosnia and Herzegovina.

Proteus anguinus lives in the subterranean fresh waters and in the aphotic biotope of the Dinaric Alps, along the Adriatic Sea, from Venetia to Herzegovina (Istria, Slovenia, Dalmatia, Croatia) (Gasc, 1997). It was introduced in the Parolini Grotto, Vicenza, northern Italy. It prefers underground water systems in Karst formations, with calm, well oxygenated water and a constant low water temperature between 6ºC (winter) and 9ºC to 12ºC (summer) (Honnegger, 1981). Proteus anguinus parkelj is found in Bela Krajina, south east Slovenia (Griffiths, 1996) (Stet and Arntzen, 1994). 

Life History, Abundance, Activity, and Special Behaviors:

Proteus anguinus lives in subterranean waters, and is therefore a difficult subject for field observations. It occurs in caves that are accessible to humans, but as these hardly contain any adults, these caves must be seen as marginal parts of the biotope. Most observations on the life history of this salamander were made in captivity. They have been bred in the Subterranean Laboratory of the CNRS, in the French Pyrenees, since 1955. The following life history account is made using data from observations on captive salamanders. Although adults aggregate in suitable spots as in cracks and under rocks, the males establish a territory when breeding, which are furiously protected from competing males. When a female enters such a territory, the courtship begins. The male fans with his tail in the direction of the female's head. The male touches the female's cloaca with his snout. The female then touches the male's cloaca with her snout and then follows the male who walks 5-10cm forward after which the male deposits a spermatophore. The pair then moves forward again until the female can take up the spermatophore with her cloaca. Courtship can be repeated several times within a few hours. 

After leaving the male's territory, the female establishes an egg-laying territory. After 2-3 days the female starts to lay eggs and can continue doing so for up to 25 days, laying a total of up to 70 eggs under rocks. The eggs are guarded by the female. The diameter of the eggs directly after laying is 4-5mm and can increase through water uptake to 8-9mm. The eggs develop in 182 days at 8ºC, in 123 days at 11ºC, and in 86 days at 15ºC. The development of larvae is highly temperature-dependent. There is no clear metamorphosis, as P. anguinus is a neotenic salamander, maintaining external gills, tail fin and other juvenile characteristics throughout its life. Sexual maturity is reached at an age of 7 years. Longevity is estimated at up to 58 years (Noellert and Noellert, 1992). It is also possible that this species is viviparous under certain circumstances, and then produces only 2 well-developed young. The diet consists of insect larvae, mostly Ephemeroptera and Plecoptera larvae, mollusks and amphipods. It can detect its prey in total darkness over some distance using chemical clues (Parzefall, 1992). In captivity worms are also readily eaten (Boehme et al, 1999). 

Trends and Threats:

The subterranean biotope is not closed. The Olm's survival is dependant on large aquatic cave systems and the conservation of sylvatic and pastoral land above. Tourism, economic changes and industrial pollution are the main threats and this species is endangered.. The decline of the known populations in Gorizia (Italy) and Postojna (Slovenia) is well established. The scientific needs can be provided by the proteus breeding program carried out by the Subterranean Laboratory of the CNRS, France. This species must be more strictly protected by law (Gasc, 1997). Honnegger (1981) also lists overcollecting, for scientific use, or as pig-food by farmers, as a threat to this species. 

Relation to Humans


Sket and Arntzen (1994) described black populations of Proteus as a separates subspecies, and defended this taxonomic decision based on the limited amount of morphological (morphometric) differentiation (Arntzen and Sket,1997) observed between the two subspecies. 

Possible reasons for amphibian decline:

  • General habitat alteration and loss
  • Local pesticides, fertilizers, and pollutants
  • Long-distance pesticides, toxins, and pollutants
  • Intentional mortality (over-harvesting, pet trade or collecting) 

Conservation Status (definitions at

2004 Jim McGuire
IUCN (Red List) ( Vulnerable (VU)
CITES ( No CITES Listing
Other International Status Listed in App. II of the Convention of European Wildlife and Natural Habitats of 1979 
National Status Protected in Slovenia since 1949. 
Regional Status None


  • Arntzen, J. W., and B. Sket (1997). "Morphometric analysis of black and white European cave salamanders, Proteus anguinus." Journal of Zoology (London), 241(4), 699-707. 
  • Boehme, W, Grossenbachre, K., Thiesmeier, B. (1999). Handbuch der Reptilien und Amphibien Europas, band 4/I:Schwanzlurche (Urodela). Aula-Verlag, Wiesbaden. 
  • Bons, J., Beniez, P (1996). Amphibiens et Reptiles du Maroc (Sahara occidental compris). Asociacion Herpetologica Española, Barcelona. 
  • Gasc, Jean-Pierre (1997). Atlas of Amphibians and Reptiles in Europe. Societas Europaea Herpetologica, Bonn, Germany. 
  • Griffiths R.A. (1996). Newts and salamanders of Europe. T. & A.D.Poyser Ltd, London. 
  • Honegger, R.E. (1981). Threatened Amphibians and Reptiles in Europe. Akademische Verlagsgesellschaft, Wiesbaden. 
  • Noellert, A.; Noellert, C. (1992). Die Aphibien Europas. Franckh-Kosmos Verlags-GmbH & co, Stuttgart. 
  • Stet, B., and J. W. Arntzen (1994). "A black, non-troglomorphic amphibian from the karst of Slovenia: Proteus anguinus parkelj n. ssp. (Urodela: Proteidae)." Bijdragen tot de Dierkunde, 64(1), 33-53. 
  • Stumpel-Rieks, S.E. (1992). Nomina Herpetofaunae Europaeae. AULA-verlag, Wiesbaden. 
  • Uiblein, F., Durand, J.P., Juberthie, C., Parzefall, J. (1992). "Predation in caves: the effects of prey immibility and darkness on the foraging behaviour of two salamanders, Euproctus asper and Proteus anguinus." Bahavioural Processes, 28, 33-40. 
  • Writer - Arie van der Meijden (University of Konstanz, Germany), modified by Meredith J. Mahoney (, Research associate, Museum of Vertebrate Zoology, UC Berkeley. 
  • Editor - Meredith J. Mahoney; JG (fixing maps 7/25/01) (2002-05-25)


  • Image -
  • AmphibiaWeb ( Information on amphibian biology and conservation. [web application]. 2002. Berkeley, California: AmphibiaWeb. Available: (Accessed: May 11, 2004) - Proteus anguinus (

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Created: Sunday, July 28, 2002; Last updated: Tuesday, October 29, 2013
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