Proteus anguinus

Laurenti 1768



see below  

There are numerous synonyms, see the Amphibians of the World webpage for a full list

Common name is Olm, or The Olm


Dinaric Karst


This species is stygobitic (i.e. aquatic)


The genus Proteus Laurenti 1768 is widely distributed on the eastern side of the Adriatic Sea and populations are currently found in Italy, Slovenia, Croatia, Bosnia Herzegovina and probably also in Montenegro (Kostanjsek et al. 2023). Currently there is only one nominal species in the genus, Proteus anguinus Laurenti 1768 with two subspecies: P. anguinus anguinus Laurenti 1768 and P. anguinus parkelj  Sket and Arntzen 1994. The first of these subspecies in troglomorphic whereas the second is pigmented and known as the “black Proteus” or “black morph”. Populations are found over a linear northwest to southeast distance of 500km and it has been hypothesized several times that these are not all the same species. There is now clear genetic evidence that there are at least nine evolutionary significant units (ESUs) across this distribution and in due course it is highly likely that all of these nine will eventually be described as separate species with their own species names. Currently (see Kostanjsek et al. 2023 and Recknagel et al. 2023 for details) there are nine named ESUs:

Ljubljanica (containing the type locailty of P. anguinus which will eventually be the only species to bear this name)




Proteus anguinus parkelj





Making 9 probable species in the genus. This will mean that there are currently 25 global species of subterranean Amphibia (16 in North and Central America and 9 in Europe).

Conservation Status

VU B2ab (ii,iii,v)

Internet Resources

Amphibians of the World



Key References

In order to save time and resources all bibliographic details for the nine Proteus species are provided under the species account for Proteus anguinus. These references are all entirely relevant to all nine known species but nothing is gained by repeating them nine times

Valvasor J.W. Book 1689 Die Ehre des Herzogthums Crain.
Laurenti J.L. Book 1768 Specimen Medicum, Exhibens Synopin Reptilium Emendatam cum Experimentis circa Venena et Antidota Reptilium Austriacorum.
Schreibers, C. von. Journal Article 1801 A historical and anatomical description of a doubtful amphibious animal of Germany called by Laurenti Proteus anguineus
Configliachi, P. and Rusconi, M. Journal Article 1821 Observations on the natural history and structure of the Proteus anguinus. Section 6. On the organs of respiration
Hochenwart, F. Journal Article 1838 Proteus anguinus
Fitzinger, L. Journal Article 1850 Ueber den Proteus anguinus der Autoren
Fejervary, G.J. Journal Article 1926 Note sur la variation du Protee et description d'individus provenants d'un nouvel habitat
Briegleb, W. Journal Article 1962 Zur Biologie und Oekologie des Grottenolms (Proteus anguinus Laur. 1768)
Briegleb, W. Journal Article 1963 Zur Kenntnis eines Ökotops von Proteus anguinus Laur.1768 (On the knowledge of the ecotope of the Proteus anguinus Laur. 1768)
Istenič, L. Journal Article 1971 Izhodišče za Reševanje Ekološke Problematike Človeške Ribice (Proteus anguinus Laur.1768.) (Approach to the solution of the problem of the ecology of Proteus)
Istenič, L. and Sojar, A. Journal Article 1972 Poraba kisika pri Močerilu - Proteus anguinus (Oxygen Consumption of Proteus anguinus)
Durand, J.P. Journal Article 1972 Recherches sur l'appareil visuel du protee, Proteus anguinus Laurenti, urodele hypoge
Thines, G. and Durand, J. Journal Article 1973 Connaissances actuelles sur l'appareil sensoriel da la ligne laterale chez les vertebres cavernicoles aquatique
Durand, J.P. Journal Article 1973 Development et involution oculaire de Proteus anguinus Laurenti Urodele cavernicole
Durand, J.P. Journal Article 1976 Rudimentation des yeux chez les poissons et urodeles souterraines
Sket, B. and Velkovrh, F. Journal Article 1978 The discovery of Proteus-eggs (Proteus anguinus Laurenti, Amphibia) in seminatural conditions
Istenič, L. Journal Article 1979 Pomanjkanje kisika v Putickovem jezeru Planinske jame (The oxygen deficit in Putick Lake of Planinska Jama)
Garasic, M. Conference Paper 1980 Pronadjena covjecja ribica (Proteus anguinus) u podzemnoj rijeci Rokine bezdane kod Jezerana u Lici
Durand, J.P. and Delay, B. Journal Article 1981 Influence of temperature on the development of Proteus anguinus (Caudata: Proteidae) and relation with its habitat in the subterranean world
Sojar, A., Istenič, L. and Musar, D. Journal Article 1981 Udisanje vazduha i problematika uloge pluća kod Proteus (Air Inhaling and problems of the role of lungs with the Proteus)
Kranjec, N. Thesis 1981 Razsirjenost in variabilnost mocerila (Proteus anguinus Laurenti)
Durand, J.P. Journal Article 1982 Donnees et hypotheses sur l'evolution des Proteidae
Istenič, L. Conference Paper 1986 Evidence of hypoxic conditions in the habitat of the cave salamander Proteus anguinus in the Planinska Jama
Aljančič, M., Habič, P. and Mihevc, A. Journal Article 1986 Črni močeril iz Bele krajine [The Black olm from White Carniola]
Bulog, B. Journal Article 1989 Differentiation of the inner ear sensory epithelia of Proteus anguinus (Urodela, Amphibia)
Aljančič, M., Bulog, B., Kranjc, A., Josipovič, D., Sket, B. and Skoberne, P. Book 1993 Proteus – The Mysterious Ruler of Karst Darkness
Sket, B. and Arntzen, J.W. Journal Article 1994 A black, non-troglomorphic amphibian from the karst of Slovenia: Proteus anguinus parkelj n. ssp. (Urodela: Proteidae)
Grillitsch, H. and Tiedemann, F. Journal Article 1994 Die Grottenolm-Typen Leopold Fitzingers (Caudata: Proteidae: Proteus)
Sket, B. Book Section 1994 "Yugoslavia" (Bosnia-Herzegovina, Croatia, Macedonia, Montenegro, Serbia, Slovenia)
Kletecki, E., Jalzic, B. and Rada, T. Journal Article 1996 Distribution of the Olm (Proteus anguinus, Laur.) in Croatia
Sket, B. Journal Article 1997 Distribution of Proteus (Amphibia: Urodela: Proteidae) and its possible explanation
Durand, J.P. Book Section 1998 Amphibia
Šolaja, M., Pocrnjić, Z. and Topalić, L. Journal Article 1998 Uticaj termičke adaptacije na bazalni metabolizam Proteusa (Proteus anguinus). (Influence of thermal adaptation on the basal metabolism of Proteus)
Dumas, P. and Chris, B. Journal Article 1998 The olfaction in Proteus anguinus: a behavioural and cytological study
Tvrtkovic, N. Journal Article 1999 Cavernicole vertebrates of the Dinaric karst
Weber, A. Book Section 2000 Fish and amphibia
Kos, M., Bulog, B., Szél, Á. and Röhlich, P. Journal Article 2001 Immunocytochemical demonstration of visual pigments in the degenerate retinal and pineal photoreceptors of the blind cave salamander (Proteus anguinus).
Tercafs, R. Book 2001 The protection of the subterranean environment: Conservation principles and management tools
Hervant, F., Mathieu, J. and Durand, J. Journal Article 2001 Behavioural, physiological and metabolic responses to long-term starvation and refeeding in a blind cave-dwelling (Proteus anguinus) and a surface-dwelling (Euproctus asper) salamander
Kletecki, E., Jalzic, B. and Rada, T. Book Section 2002 Amphibia
Bulog, B. Book Section 2004 Amphibia: Proteus
Weber, A. Book Section 2004 Amphibia
Sket, B., Paragamian, K. and Trontelj, P. Book Section 2004 A census of the obligate subterranean fauna of the Balkan peninsula
Sket, B. Book Section 2004 Dinaric Karst: Biospeleology
Durand, J.P. Book Section 2005 Salamanders
Sket, B. Book Section 2005 Dinaric Karst, Diversity in
Gorički, Š. and Trontelj, P. Journal Article 2006 Structure and evolution of the mitochondrial control region and flanking sequences in the European cave salamander Proteus anguinus
Trontelj, P., Gorički, Š., Polak, S., Verovnik, R., Zakšek, V. and Sket, B. Journal Article 2007 Age estimates for some subterranean taxa and lineages in the Dinaric Karst
Schlegel, P.A., Steinfartz, S. and Bulog, B. Journal Article 2009 Non-visual sensory physiology and magnetic orientation in the blind cave salamander, Proteus anguinus (and other cave-dwelling urodele species): review and new results on light-sensitivity and non-visual orientation in subterranean urodeles (Amphibia)
Issartel, J., Hervant, F., de Fraipont, M., Clobert, J.and Voituron, Y. Journal Article 2009 High anoxia tolerance in the subterranean salamander Proteus anguinus without oxidative stress nor activation of antioxidant defenses during reoxygenation
Pezdirc, M., Heath, E., Mali, L.B. and Bulog, B. Journal Article 2011 PCB accumulation and tissue distribution in cave salamander (Proteus anguinus anguinus, Amphibia, Urodela) in the polluted karstic hinterland of the Krupa River, Slovenia
Voituron, Y., de Fraipont, M., Issartel, J., Guillaume, O. and Clobert, J. Journal Article 2011 Extreme lifespan of the human fish (Proteus anguinus): a challenge for ageing mechanisms
Goricki, S., Niemiller, M.L. and Fenolio, D.B. Book Section 2012 Salamanders
Hajna, N.Z. Book Section 2012 Dinaric Karst: Geography and geology
Sket, B. Book Section 2012 Diversity patterns in the Dinaric karst
Hervant, F. Book Section 2012 Starvation in subterranean species versus surface-dwelling species: Crustaceans, Fish, and Salamanders
Ivanović, A., Aljančič, G. and Arntzen, J.W. Journal Article 2013 Skull shape differentiation of black and white olms (Proteus anguinus anguinus and Proteus a. parkelj): An exploratory analysis with micro-CT scanning
Manenti, R. and Ficetola, G.F. Journal Article 2013 Salamanders breeding in subterranean habitats: local adaptations or behavioural plasticity?
Jelić, D. et al. Journal Article 2014 A survival blueprint for Olm, Proteus anguinus
Sessions, S., Bulog, B. and Mali, L.B. Journal Article 2015 The phoenix rises: Reversal of cave adaptations in the blind cave salamander, Proteus anguinus?
Prelovšek, M. Journal Article 2016 Proteus survival close to an industrial, agricultural and urbanized basin - the case of Kočevsko polje
Niemiller, M.L., Zigler, K.S., Stephen, C.D.R., Carter, E.T., Paterson, A.T., Taylor, S.J. and Engel, A.S. Journal Article 2016 Vertebrate fauna in caves of eastern tennessee within the Appalachians karst region, USA
Bizjak Mali. L. and Bulog, B. Journal Article 2016 Functional morphology and environmental studies on Proteus
Năpăruș-Aljančič, M., Gorički, Š., Stanković, D., Kuntner, M. and Aljančič, G. Journal Article 2017 GIS analysis to assess the groundwater habitat pollution of black proteus
Bonacci, O. Book 2017 Karst Hydrology : With Special Reference to the Dinaric Karst
Gorički, S., Stanković, D., Snoj, A., Kuntner, M., Jeffery, W.R., Trontelj, P., Pavićević, M., Grizelj, Z., Năpăruş-Aljančič, M. and Aljančič, G. Journal Article 2017 Environmental DNA in subterranean biology: range extension and taxonomic implications for Proteus
Vörös, J., Márton, O., Schmidt, B.R., Gál, J.T., & Jelić, D. Journal Article 2017 Surveying Europe's only cave-dwelling chordate species (Proteus anguinus) using environmental DNA.
Bizjak-Mali, L. Journal Article 2017 Variability of testes morphology and the presence of testis-ova in the European blind cave salamander (Proteus anguinus)
Vörös, J., Ursenbacher, S. and Jelić, D. Journal Article 2018 Population genetic analyses using 10 new polymorphic microsatellite loci confirms genetic subdivision within the olm, Proteus anguinus
Zakšek, V., Konec, M. and Trontelj, P. Journal Article 2018 First microsatellite data on Proteus anguinus reveal weak genetic structure between the caves of Postojna and Planina
Gladstone, N.S., Carter, E.T., Niemiller, K.D.K., Hayter, L.E. and Niemiller, M.L. Journal Article 2018 A new maximum body size record for the Berry Cave Salamander (Gyrinophilus gulolineatus) and genus Gyrinophilus (Caudata, Plethodontidae) with a comment on body size in plethodontid salamanders
Jelic, D. Book Section 2018 Croatia.Cave Fauna. IX 1. Cave aquatic fauna
Aljančič, G. Journal Article 2019 History of research on Proteus anguinus Laurenti 1768 in Slovenia
Kostanjšek, R., Prodan, Y., Stres, B. and Trontelj, P. Journal Article 2019 Composition of the cutaneous bacterial community of a cave amphibian, Proteus anguinus
Gorički, Š., Niemiller, M.L., Fenolio, D.B. and Gluesenkamp, AG. Book Section 2019 Salamanders
Šarić, K.K., Jelić, D., Konrad, P.K. and Jalžić, B. Book 2019 Proteus
Kolar, B. Journal Article 2019 The threshold concentration for nitrate in groundwater as a habitat of Proteus anguinus
Mulec, J. Journal Article 2020 Interview with Rok Kotanjšek and Nina Gunde-Cimerman. Welcome to the -omics era of the 21st century: will Proteus anguinus finally reveal all its mysteries?
Balázs, G., Lewarne, B. and Herczeg, G. Journal Article 2020 Extreme site fidelity of the olm (Proteus anguinus) revealed by a long-term capture–mark–recapture study
Li. Z., Verbrugghe, E., Konstanjšek, R., Lukač, M., Pasmans, .F, Cizelj., I. and Martel, A. Journal Article 2020 Dampened virulence and limited proliferation of Batrachochytrium salamandrivorans during subclinical infection of the troglobiont olm (Proteus anguinus)
Gredar, T. Thesis 2020 Development of non-destructive approaches for sex identification in the Proteus (Proteus anguinus, Urodela, Amphibia)
Lewarne, B. and Balázs, G. Journal Article 2020 Observed air-breathing behaviour of Proteus anguinus individuals under an intermittent hypoxic scenario in their natural habitat, with details of the prevailing environmental conditions
Lewarne, B. and Allain, S.J.R. Journal Article 2020 The unnatural history of cave olms Proteus anguinus in England
Whittaker, K. and Koo, M.S. Web Page 2021 Proteus anguinus: Olm
Garasic, M. Book 2021 The Dinaric Karst System of Croatia. Speleology and Cave Exploration
Niemiller, M.L., Carter, E.T., Fenolio, D.B., Gluesenkamp, A.G. and Phillips, J.G. Book Section 2022 Subterranean colonisation and diversification of cave-dwelling salamanders
Niemiller, M.L., Carter, E.T., Gladstone, N.S., Niemiller, K.D.K., Hayter, L.E., Engel, A.S., Miller, B.T., and Fitzpatrick, B.M. Journal Article 2022 The distribution, ecology, life history, and conservation status of the Berry Cave salamander (Gyrinophilus gulolineatus)
Tesarová, M., Mancini, L., Mauri, E., Aljancic, G., Naparus-Aljancic, M., Kostanjšek, R., Mali, L.B., Zikmund, T., Kaucká, M., Papi, F., Goyens, J., Bouchnita, A., Hellander, A. Journal Article 2022 Living in darkness: Exploring adaptation of Proteus anguinus in 3 dimensions by X-ray imaging
Kostanjšek, R. et al. Journal Article 2022 Towards the massive genome of Proteus anguinus, illuminating longevity, regeneration, convergent evolution and metabolic disorders
Guillaume, O. Conference Paper 2022 The cave salamander Proteus anguinus in captivity in Moulis, France for the scientific research
Barzaghi, B., Ficetola, F.G., Mauri, E., Restaino, M., Lombardi, B. and Manenti, R. Conference Paper 2022 Preliminary study on differences characterizes the populations of olm (Proteus anguinus) in cave and those found in epigean environment
Ravbar, N., Viršek, D. and Năpăruş-Aljančič, M. Journal Article 2023 New locality of Proteus anguinus in the area of the Tabor Ridge near Grosuplje, central Slovenia
Petrescu-Mag, V. Journal Article 2023 The olm (Proteus anguinus) and cave life
Voituron, Y., Guillaume, O., Dumet, A., Zahn. S and Criscuolo, F. Journal Article 2023 Temperature-independent telomere lengthening with age in the long-lived human fish (Proteus anguinus)
Lewarne, B. and Allain, S.J.R. Journal Article 2023 Attempted predation of a cave olm Proteus anguinus by a dice water snake Natrix tessellata, in Bosnia and Herzegovina
Barzaghi, B. Thesis 2023 Between light and darkness: The round-trip of surface and subterranean animals
Recknagel, H., Zakšek, V., Delić, T., Gorički, S. and Trontelj, P. Journal Article 2023 Multiple transitions between realms shape relict lineages of Proteus cave salamanders
Kostanjsek, R., Zaksek, V., Bizjak-Mali, L. and Trontelj, P. Book Section 2023 Chapter 13. The olm (Proteus anguinus), a flagship groundwater species
Anonymous Web Page 2024 Wikipedia: Olm
Manenti, R., Vinci, L., Barzaghi, B., Lombardi, B., Teodoro, C., Baglioni, L., Melotto, A. and Francesco Ficetola, G. Journal Article 2024 Sit-and-wait foraging is not enough in food-deprived environments: evidence from groundwater and salamanders