The olm is a blind, pale salamander that lives only in underground waters of southern Europe’s caves. It is one of the most extraordinary examples of adaptation to life in darkness.
Interesting facts
- It is blind, with tiny eyes hidden under its skin.
- Its pale pink skin earned it the local nickname ‘human fish’.
- Olms keep their feathery gills throughout their lives.
- They can survive for years without food.
- People once thought olms were baby dragons washed out of caves by floods.
- Olms hatched from eggs in Slovenia’s Postojna Cave in 2016, a rare event followed around the world.
Behaviour
Olms move slowly through dark underground waters, using smell, hearing and sensitivity to electric fields to find prey. They use very little energy.
Breeding and young
Females lay about 35–70 eggs under rocks and guard them. The eggs take several months to hatch, and young take about 14 years to mature.
Threats and conservation
Pollution of underground water from farms, industry and towns, and changes to cave habitats.
Where to see it
- Postojna Cave and its Proteus Vivarium, Slovenia
- Vivarium Proteus, Postojna
- Caves of the Croatian Karst (in special exhibits)
- Not visible in the wild; they live deep underground
Status source: IUCN Red List. Profile last reviewed September 2026.
