# Olm (*Proteus anguinus*)

> The olm (Proteus anguinus) is a blind, pale cave salamander of Dinaric Alps karst waters in Slovenia, Croatia, and Bosnia. It can live for decades, survives years without food, eats cave crustaceans and worms, and is listed Vulnerable as groundwater pollution and habitat disturbance threaten subterranean aquifers.

- **Category:** Amphibian
- **Conservation status (IUCN):** Vulnerable
- **Range:** Underground karst waters of the Dinaric Alps in Slovenia, Croatia, and Bosnia.
- **Canonical page:** https://globalanimalguide.org/animals/olm/
- **Last reviewed:** 2026-07-16

## Scientific classification

- **Kingdom:** Animalia
- **Phylum:** Chordata
- **Class:** Amphibia
- **Order:** Urodela
- **Family:** Proteidae
- **Genus:** Proteus

## Facts at a glance

| Attribute | Value |
| --- | --- |
| Scientific name | Proteus anguinus |
| Diet | Carnivore (cave invertebrates) |
| Habitat | Subterranean limestone caves and aquifers |
| Lifespan | Around 70 years in the wild (varies by population and captivity). |
| Weight | About 0.02 kg typical adult mass (sex and region vary). |
| Top speed | Up to roughly 1 km/h when moving at speed. |
| Conservation status | Vulnerable (IUCN) |

## Blind life underground

Eyes are regressed under skin; olms navigate by smell, water pressure, and electroreception. External gills and a elongated body suit permanent aquatic life in darkness. Skin is translucent pinkish-white.

## Sparse cave prey

They eat small crustaceans, worms, and other invertebrates washed into or living in cave streams. Metabolism is extremely slow — individuals can endure long fasts.

## Dinaric karst aquifers

Subterranean limestone caves and aquifers of the Dinaric Alps — Slovenia's Postojna region is famous — plus Croatia and Bosnia. Across its range it is tied to subterranean limestone caves and aquifers, and field accounts emphasise this species’ distinctive ecology rather than generic habitat labels.

## Vulnerable groundwater icon

IUCN lists olms Vulnerable. Industrial and agricultural pollution entering karst sinks, water extraction, and tourist cave traffic can harm populations that reproduce rarely.

## Frequently asked questions

### Why are olms white and blind?

Living in perpetual darkness, they lost functional eyes and pigment — classic cave-animal traits.

### How long can an olm live?

Decades; some estimates suggest lifespans approaching a century under ideal conditions.

### Can olms go years without eating?

Yes — their slow metabolism allows survival through long periods of scarce food.

### Where do olms live?

Underground karst waters of the Dinaric Alps in Slovenia, Croatia, and Bosnia.

### Are olms protected?

Yes — they are legally protected in their range countries and listed Vulnerable by IUCN.

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Source: Global Animal Guide (https://globalanimalguide.org/animals/olm/). Licensed CC BY-NC 4.0 — free for non-commercial reuse with attribution.