Facts
  • Found in Bosnia & Herzegovina, Croatia, Slovenia, possibly found in Serbia & Montenegro.
  • Introduced into caves in France and Italy.
  • The olm is Europe’s only cave-adapted vertebrate.
  • Native to the Dinaric Karst system of Eastern Europe, where it inhabits streams and pools within these limestone caves. Its eyes are much-reduced as a result of the permanent darkness in which this species lives, so it hunts for cave invertebrates using electo-sensitivity and a powerful sense of smell.
  • Although it appears to be albino, olms are still capable of producing melanin and turn brown/black if exposed to sunlight.
  • They are very long-lived, with a confirmed maximum longevity of up to 58 years (although it has been suggest that they may reach 100 years or more), and can survive for over 10 years without food.
Threats
  • Changes to the forested and pastoral land above the subterranean systems, largely through tourism, economic changes and increasing water contamination. This species is highly dependent on clean water and is therefore very susceptible to pollution.
  • Illegal collection of this species for the pet trade is also a potential problem, but the extent of this is unknown.
  • The olm is classified as Vulnerable in the IUCN Red List of Threatened Species because its area of occupancy is less than 2,000 km2, its distribution is severely fragmented, and there is continuing decline in the extent and quality of its habitat, and in the number of mature individuals.
Conservation Required
  • Funding an EDGE Fellow to collect more data on the distribution this species because so little is currently known – this information can then be used to create a Conservation Action Plan.


Proposed Actions

EDGE would like to fund an EDGE Fellow to carry out surveys on the distribution of the species in Slovenia, which is currently very poorly known.

The olm is Europe’s only cave-adapted vertebrate, inhabiting streams and pools within the limestone caves of Eastern Europe. This species’ eyes are much-reduced as a result of the permanent darkness in the cave habitat, so it hunts for cave invertebrates using electro-sensitivity and a powerful sense of smell. Olms are long-lived creatures, with a confirmed maximum age of 58 years (although it is thought that the species may reach 100 years or more), and can survive for over ten years without food.

The olm is highly susceptible to pollution, and unfortunately changes to the forested and pastoral land above the subterranean systems, as a result of tourism and economic changes, have increased water contamination of the olm’s habitat. As a result, the species has been classified as Vulnerable on the IUCN Red List of Threatened Species.

EDGE hopes to fund research into the distribution of the olm in Slovenia so that the range of this species is more accurately known; currently it is suspected that the olm may be found beyond the existing confirmed range, however this needs verification by field studies. This research is required to feed into a Conservation Action Plan for the olm and may identify additional threats to this species that need to be addressed.

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