---
title: "What the sources say about the Olm | AnimalTracks.wiki"
description: "47 claims from the Olm profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/olm-1.webp"
canonical: "https://animaltracks.wiki/animals/olm/sources/"
---

# What the sources say about the Olm (*Proteus anguinus*)

> 47 claims from the Olm profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Olm](https://animaltracks.wiki/animals/olm/)

## Proteus anguinus (olm). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Proteus_anguinus/

| The page says | The source says |
| :--- | :--- |
| Underground lakes and streams of limestone caves | Proteus anguinus is found in the subterranean, freshwater lakes and streams of limestone caves in the Dinaric Alps. (note: covers stats.habitat and the body's opening sentence ('the underground lakes and streams of limestone caves').) |
| Amphipods, isopods, small snails, and insect larvae | They prey on arthropods and small invertebrates such as Oniscus asellus as well as organsims of the genera Belgrandiella and Niphargus. They also feed on a wide variety of insect larvae (note: covers stats.diet; Niphargus = amphipod genus, Oniscus asellus = isopod, Belgrandiella = small freshwater snail genus.) |
| lives a salamander with greatly reduced eyes | Its eyes still retain some light sensitivity, but they are greatly reduced. |
| A young olm (*Proteus anguinus*) has better developed eyes than an adult | Juveniles may be distinguished from adults by the faint yellow or red blotches on their skin, and their better developed eyes. |
| whose eyes are very small and do not even breach the skin | Its eyes are very small and do not even breach the skin. |
| it has skin on its underside translucent enough to reveal the contours of its internal organs | On the ventral side of the body the skin is translucent and reveals the contours of internal organs. |
| An olm's skin is usually creamy white to pale pink | The skin is usually creamy white, but may have a pinkish hue. |
| exposed to light it turns dark violet to black, and the darkening reverses once it is back in the dark | When exposed to light, the skin turns dark violet to black. Darkening of the skin is reversed when it is returned to the darkness. |
| Behind its head sit three feathery pink gills on each side | Directly behind the head on each side are three large, feathery, bright pink gills. |
| the olm is neotenic | Development - Life Cycle neotenic/paedomorphic |
| Hatchlings skip a distinct period of metamorphosis and develop directly into adults, retaining some larval features such as their gills and finned tail | olm larvae do not go through a distinct period of metamorphosis. Instead, the hatchling juveniles have developed directly into adults, retaining some of their larval characters such as gills and tail fins. |
| It hunts amphipods, isopods, small snails and insect larvae | They prey on arthropods and small invertebrates such as Oniscus asellus as well as organsims of the genera Belgrandiella and Niphargus. They also feed on a wide variety of insect larvae (note: Niphargus = amphipod genus, Oniscus asellus = isopod, Belgrandiella = small freshwater snail genus; common names used in place of the Latin names ADW gives.) |
| in water generally more than 300 metres below the surface | They are generally found over 300 meters below surface. |
| Its eyes keep some light sensitivity, but the olm leans on non-visual senses | Proteus anguinus has developed non-visual sensory systems to better suit an aphotic lifestyle. Its eyes still retain some light sensitivity, but they are greatly reduced. |
| are suspected to help it locate prey by detecting electric fields | All members of the genus Proteus contain an ampullary electroreceptor which is used to detect electric fields. The main function of their ampullary electroreceptor is not known, but it is suspected top be used for locating prey. |
| 20 to 30 centimetres long | Range length 20 to 30 cm |
| tops out around 30 centimetres long | Range length 20 to 30 cm (note: upper end of ADW's 20-30 cm range.) |
| eyes buried under its skin | Its eyes are very small and do not even breach the skin. |
| Behavioural studies suggest olms can also detect and orient to magnetic fields | Behavioral studies suggest that Proteus anguinus is also able to detect and orient itself to magnetic fields. |
| To find prey they combine chemoreceptors, electroreceptors and mechanoreceptors | To locate and capture their prey, olms use a combination of chemoreceptors, electroreceptors, and mechanoreceptors. |
| Its eyes do not even breach the skin | Its eyes are very small and do not even breach the skin. (note: vibe.reason (settle #880)) |

## Miaud et al. (2024). Proteus anguinus. The IUCN Red List of Threatened Species 2024: e.T18377A227229041.

https://doi.org/10.2305/iucn.uk.2024-2.rlts.t18377a227229041.en

| The page says | The source says |
| :--- | :--- |
| The IUCN lists the species as Vulnerable | IUCN Red List category: Vulnerable (VU). Proteus anguinus Laurenti, 1768 (note: Category read through GBIF's copy of the Red List, per docs/fact-check.md (iucnredlist.org refuses scripts).) |

## Voituron et al. (2010). Extreme lifespan of the human fish (Proteus anguinus): a challenge for ageing mechanisms. Biology Letters.

https://doi.org/10.1098/rsbl.2010.0539

| The page says | The source says |
| :--- | :--- |
| Known as the "human fish" | we show that the 'human fish' (olm, Proteus anguinus) |
| 15 to 20 grams | a small cave salamander (weighing 15-20 g) |
| a predicted maximum lifespan of over 100 years | a predicted maximum lifespan of over 100 years |
| The same study put the average adult lifespan at 68.5 years | an adult average lifespan of 68.5 years |
| on average a female lays 35 eggs every 12.5 years | lays, on average, 35 eggs every 12.5 years |
| sexual maturity arrives at about 15.6 years old | an age at sexual maturity of 15.6 years |
| a predicted lifespan past 100 years | a predicted maximum lifespan of over 100 years |
| Predicted 100-year-plus lifespan | a predicted maximum lifespan of over 100 years |
| A 2010 study predicted a maximum lifespan of over 100 years | a predicted maximum lifespan of over 100 years (note: 2010 is the paper's publication year (Biology Letters, published online 2010).) |
| which makes the 15 to 20 gram olm an outlier among amphibians for its size | a small cave salamander (weighing 15-20 g) ... this animal sits as an outlier in the amphibian size/longevity relationship |
| weightKg: 0.018 | a small cave salamander (weighing 15-20 g) (note: battleStats (settle #880)) |

## Bizjak Mali, Sepčić & Bulog (2013). Long-term starvation in cave salamander effects on liver ultrastructure and energy reserve mobilization. Journal of Morphology.

https://doi.org/10.1002/jmor.20145

| The page says | The source says |
| :--- | :--- |
| Deprived of food, an olm's liver uses up its glycogen first and turns to lipids and proteins later | Glycogen is rapidly utilized at the beginning of the starvation period, whereas lipids and proteins are utilized subsequently, during prolonged food deprivation. |
| one study kept olms without food for 18 months, the length of its longest treatment rather than a measured limit | after food deprivation periods of one and 18 months were investigated (note: 18 months is the longer of the study's two treatments; the paper reports no survival limit.) |
| an experimental fast of a year and a half | after food deprivation periods of one and 18 months were investigated (note: 18 months is a year and a half; the length of a treatment, not a survival limit.) |
| an 18-month experimental fast | after food deprivation periods of one and 18 months were investigated |
| At least 18 months: that was the longer of the two fasts in one study, not a measured limit | after food deprivation periods of one and 18 months were investigated |
| By then their liver cells had shrunk and held fewer fat droplets, yet the liver's integrity was apparently maintained | After 18 months of food deprivation hepatocytes were reduced in size, lipid droplets were less numerous ... The liver integrity was apparently maintained |

## Sket (1997). Distribution of Proteus (Amphibia: Urodela: Proteidae) and its possible explanation. Journal of Biogeography.

https://doi.org/10.1046/j.1365-2699.1997.00103.x

| The page says | The source says |
| :--- | :--- |
| spread across Italy, Slovenia, Croatia, and Bosnia and Herzegovina | it ranges from the Isonzo‐Soća River in southeastern Venezia Giulia, Italy, through the southern half of Slovenia, southern Croatia, and parts of Bosnia and Hercegovina, to the Trebišnica River in eastern Hercegovina |
| Dinaric Karst of Italy, Slovenia, Croatia, and Bosnia and Herzegovina | The species is limited to the Dinaric Karst; it ranges from the Isonzo‐Soća River in southeastern Venezia Giulia, Italy, through the southern half of Slovenia, southern Croatia, and parts of Bosnia and Hercegovina (note: covers stats.habitat, worded to match the field's own text.) |
| By 1997, pollution and human-made changes to water flow had wiped out or endangered populations in some regions | In some regions, populations have been extinguished or endangered by pollution or human‐induced hydrographical changes. (note: 1997 is the publication year of Sket's survey, which dates the statement.) |

## Dumas & Chris (1998). The olfaction in Proteus anguinus: a behavioural and cytological study. Behavioural Processes.

https://doi.org/10.1016/s0376-6357(98)00002-3

| The page says | The source says |
| :--- | :--- |
| in experiments, an olm's sense of smell reached its detection threshold at about 1 gram of prey, in a water current of 250 cubic centimetres a minute | Proteus shows a well-developed olfactive sense: the sensitivity threshold occurs around 1 g of prey (in a 250 cm(3)/min water current). |

## Istenič & Bulog (1984). Some evidence for the ampullary organs in the European cave salamander Proteus anguinus (Urodela, Amphibia). Cell and Tissue Research.

https://doi.org/10.1007/bf00217865

| The page says | The source says |
| :--- | :--- |
| Its ampullary organs, small pits in the skin | Their fundamental structure consists of single ampullae with sensory and accessory cells with apical parts that extend into the pit of the ampulla, and of a short jelly-filled canal connecting the ampulla pit with the surface of the skin. |
| are built like electroreceptors | support the view that the morphologically-identified ampullary organs are electroreceptive |
| electroreceptive ampullary organs | the morphologically-identified ampullary organs are electroreceptive |
| small pits in its skin built like electroreceptors | support the view that the morphologically-identified ampullary organs are electroreceptive (note: vibe.reason (settle #880)) |