Editing Olm (section)

==Ecology and life history==
[[file:P anguinus1.jpg|thumb|The olm swims by serpentine bending of the body.]]

The olm lives in well-oxygenated underground waters with a typical, very stable temperature of {{convert|8-11|C|F|abbr=on}}, infrequently as warm as {{convert|14|C|F|abbr=on}}.<ref name="AW" /> There have also been observations in northeastern Italy where they swim to the surface in springs outside the caves, even in daylight, where they occasionally feed on earthworms.<ref>{{cite journal |last1=Manenti |first1=Raoul |title=Wandering outside of the Styx: Surface activity of an iconic subterranean vertebrate, the olm (Proteus anguinus) |journal=The Scientific Naturalist |date=February 8, 2024 |volume=105 |issue=3 |pages=e4252 |doi=10.1002/ecy.4252 |pmid=38329178 |bibcode=2024Ecol..105E4252M |url=https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecy.4252 |access-date=25 April 2024|hdl=2434/1036228 |hdl-access=free }}</ref> The black olm may occur in surface waters that are somewhat warmer.<ref name="AW" />

[[Image:P anguinus-head.jpg|thumb|right|Disproportionately elongated head with gills]]

The olm swims by eel-like twisting of its body, assisted only slightly by its poorly developed legs. It is a [[predator]]y animal, feeding on small [[crustacean]]s (for example, ''[[Troglocaris]]'' shrimp, ''[[Niphargus]]'', ''[[Asellus]]'', and ''Synurella'' amphipods, and ''[[Oniscus asellus]]''), [[snail]]s (for example, ''[[Belgrandiella]]''), and occasionally [[insect]]s and insect larvae (for example, [[Trichoptera]], [[Ephemeroptera]], [[Plecoptera]], and [[Diptera]]).<ref name="animal" /><ref name="Jugovic2015">{{Cite journal |last1=Jugovic E. |last2=J.E. Praprotnik |last3=V. Buzan |last4=M. Lužnik |year=2015 |title=Estimating population size of the cave shrimp Troglocaris anophthalmus (Crustacea, Decapoda, Caridea) using mark–release–recapture data |journal=Animal Biodiversity and Conservation |volume=38 |issue=1 |pages=77–86|doi=10.32800/abc.2015.38.0077 |doi-access=free }}</ref><ref>{{cite web | url = https://animaldiversity.org/accounts/Proteus_anguinus/ | title = Proteus anguinus | website = Animal Diversity Web | last = Meaton | first = J. | date = 2011 | access-date = 1 January 2023}}</ref><ref>{{cite web | url = https://amphibiaweb.org/species/4229 | title = Proteus anguinus | website = AmphibiaWeb | date = 2021}}</ref> It does not chew its food, instead swallowing it whole. The olm is resistant to long-term starvation, an adaptation to its underground habitat. It can consume large amounts of food at once, and store nutrients as large deposits of [[lipid]]s and [[glycogen]] in the [[liver]]. When food is scarce, it reduces its activity and [[metabolism|metabolic rate]], and can also reabsorb its own tissues in severe cases. Controlled experiments have shown that an olm can survive up to 10 years without food.<ref name="BUL02">{{Cite journal |last=Bulog |first=B. |date=1994 |title=Dve desetletji funkcionalno-morfoloških raziskav pri močerilu (Proteus anguinus, Amphibia, Caudata) |trans-title=Two decades of functional-morphological research on the olm (''Proteus anguinus, Amphibia, Caudata'') |url=http://www.dlib.si/details/URN:NBN:SI:DOC-VJMGI7ZT |journal=Acta Carsologica |language=sl |volume=23 |pages=248–263}}</ref>

Olms are [[Social animal|gregarious]], and usually aggregate either under stones or in fissures.<ref name="GUI01">{{Cite journal |last=Guillaume |first=O |date=2000 |title=Role of chemical communication and behavioural interactions among conspecifics in the choice of shelters by the cave-dwelling salamander Proteus anguinus (Caudata, Proteidae) |journal=Can. J. Zool. |volume=78 |issue=2 |pages=167–173 |doi=10.1139/z99-198|bibcode=2000CaJZ...78..167G }}</ref> Sexually active males are an exception, establishing and defending territories where they attract females. The scarcity of food makes fighting energetically costly, so encounters between males usually only involve [[Display (zoology)|display]]. This is a behavioral adaptation to life underground.<ref name="ALJ01" />

===Breeding and longevity===
Reproduction has only been observed in captivity so far.<ref name="ALJ01" /><ref>{{cite journal | last=Aljančič | first=Gregor | title=History of research on ''Proteus anguinus'' Laurenti 1768 in Slovenia | journal=Folia Biologica et Geologica | volume=60 | issue=1 | date=2019-07-25 | doi=10.3986/fbg0050 | page=39| doi-access=free }}</ref> Sexually mature males have swollen cloacas, brighter skin color, two lines at the side of the tail, and slightly curled fins. No such changes have been observed in the females. The male can start courtship even without the presence of a female. He chases other males away from the chosen area, and may then secrete a female-attracting [[pheromone]]. When the female approaches, he starts to circle around her and fan her with his tail. Then he starts to touch the female's body with his snout, and the female touches his cloaca with her snout. At that point, he starts to move forward with a twitching motion, and the female follows. He then deposits the [[spermatophore]], and the animals keep moving forward until the female hits it with her cloaca, after which she stops and stands still. The spermatophore sticks to her and the [[sperm]] cells swim inside her cloaca, where they attempt to fertilize her eggs. The courtship ritual can be repeated several times over a couple of hours.<ref name="ALJ01" />

The female lays up to 70 eggs, each about {{convert|12|mm|in|1}} in diameter, and places them between rocks, where they remain under her protection.<ref name="AA01">{{cite journal|last1=Aljančič |first1=G.|last2= Aljančič |first2=M. |year=1998|url=https://www.tular.si/images/pdf/GM_Aljancic_1998_Razmnozevanje_cloveske_ribice.pdf |title=Žival meseca oktobra: Človeška ribica (Proteus anguinus) |trans-title=The animal of the month of October: olm|journal=Proteus|volume=61|issue=2|pages=83–87|lang=sl}}</ref> The average is 35 eggs and the adult female typically breeds every 12.5 years.<ref name="Voituron2010">{{Cite journal |last1=Voituron |first1=Y. |last2=De Fraipont |first2=M. |last3=Issartel |first3=J. |last4=Guillaume |first4=O. |last5=Clobert |first5=J. |year=2010 |title=Extreme lifespan of the human fish (Proteus anguinus): a challenge for ageing mechanisms |journal=Biology Letters |volume=7 |issue=1 |pages=105–107 |doi=10.1098/rsbl.2010.0539 |pmc=3030882 |pmid=20659920}}</ref> The tadpoles are {{convert|2|cm|in|1}} long when they hatch and live on [[yolk]] stored in the cells of the digestive tract for a month.<ref name="AA01" />

At a temperature of {{convert|10|C|F|abbr=on}}, the olm's [[embryo]]nic development (time in the eggs before hatching) is 140 days, but it is somewhat slower in colder water and faster in warmer, being as little as 86 days at {{convert|15|C|F|abbr=on}}. After hatching, it takes another 14 years to reach sexual maturity if living in water that is {{convert|10|C|F|abbr=on}}.<ref name="AW" /><ref name="DUR02">{{Cite journal |last1=Durand |first1=J.P. |last2=Delay |first2=B. |date=1981 |title=Influence of temperature on the development of ''Proteus anguinus'' (Caudata: Proteidae) and relation with its habitat in the subterranean world |journal=Journal of Thermal Biology |volume=6 |issue=1 |pages=53–57 |doi=10.1016/0306-4565(81)90044-9|bibcode=1981JTBio...6...53D }}</ref> The larvae gain adult appearance after nearly four months, with the duration of development strongly correlating with water temperature.<ref name="DUR02" /> Unconfirmed historical observations of [[viviparity]] exist, but it has been shown that the females possess a [[gland]] that produces the egg casing, similar to those of [[fish]] and egg-laying amphibians.<ref name="ALJ01">Aljančič M., Bulog B. et al. (1993). ''Proteus&nbsp;– mysterious ruler of Karst darkness''. Ljubljana: Vitrium d.o.o. {{in lang|sl}}</ref> [[Paul Kammerer]] reported that female olm gave birth to live young in water at or below {{convert|55|F|C|abbr=on|order=flip}} and laid eggs at higher,{{r|ley196802}} but rigorous observations have not confirmed that. Historical reports of viviparity have long been attributed to scientific fraud, but may have alternatively resulted from the olms tendency to regurgitate food due to stress. These food items, including juvenile salamanders, may have been misinterpreted as their offspring.<ref>{{Cite journal |last=Recknagel |first=Hans |last2=Premate |first2=Ester |last3=Zakšek |first3=Valerija |last4=Aljančič |first4=Gregor |last5=Kostanjšek |first5=Rok |last6=Trontelj |first6=Peter |date=2022-04-07 |title=Oviparity, viviparity or plasticity in reproductive mode of the olm Proteus anguinus: an epic misunderstanding caused by prey regurgitation? |url=https://brill.com/view/journals/ctoz/91/3/article-p153_001.xml |journal=Contributions to Zoology |volume=91 |issue=3 |pages=153–165 |doi=10.1163/18759866-bja10029 |issn=1875-9866}}</ref> Regardless, the olm appears to be exclusively [[ovipary|oviparous]].<ref>{{Cite book |title=Reproductive biology and phylogeny of Urodela |date=2003 |publisher=Science Publishers |isbn=1578082854 |editor-last=Sever, David M. |page=449}}</ref>

Development of the olm and other [[troglobite]] amphibians is characterized by [[heterochrony]]&nbsp;– the animal does not undergo [[metamorphosis]] and instead retains larval features. The form of heterochrony in the olm is [[neoteny]]&nbsp;– delayed [[Somatic (biology)|somatic]] maturity with precocious reproductive maturity, i.e. reproductive maturity is reached while retaining the larval external [[morphology (biology)|morphology]]. In other amphibians, the metamorphosis is regulated by the [[hormone]] [[thyroxine]], secreted by the [[thyroid]] gland. The thyroid is normally developed and functioning in the olm, so the lack of metamorphosis is due to the unresponsiveness of key [[Tissue (biology)|tissues]] to thyroxine.<ref name="LANG01" />

Longevity is estimated at up to 58 years.<ref>Noellert A., Noellert C. (1992). ''Die Aphibien Europas''. Franckh-Kosmos Verlags GmbH & co., Stuttgart.{{in lang|de}}</ref> A study published in ''[[Biology Letters]]'' estimated that they have a maximum lifespan of over 100 years and that the lifespan of an average adult is around 68.5 years. When compared to the longevity and body mass of other amphibians, olms are [[outlier]]s, living longer than would be predicted from their size.<ref name=Voituron2010/>