Olm

Where does the olm live?

Home: Cold, dark water inside limestone caves.

In the wild it lives in these countries: Slovenia, Croatia, Bosnia and Herzegovina, Italy.

Conservation status from the IUCN: vulnerable.

The short profile

Fully grown: about 25 cm long. It weighs about 0.02 kilograms. On the menu: meat.

The story behind it

Deep under the karst hills of Slovenia, Croatia and Bosnia and Herzegovina, water runs through cracks and caves that never see daylight. The olm lives there and nowhere else. Because there is nothing to see, its eyes stopped developing and are covered by skin, but it finds prey by smell, by taste, by the tiniest movements in the water and even by sensing weak electric fields. It is about twenty-five centimetres long, with a slim body, four small legs and three feathery red gills on each side of its head. It eats cave shrimps, snails and insect larvae, and when food runs out it slows its body right down and can survive for years without eating at all. Olms grow up very slowly, breed roughly once a decade and can live for more than a hundred years. Long ago, local people who found pale creatures washed out of caves after storms believed they were baby dragons. Today the caves are protected, because dirty water sinking from the fields above reaches them easily.

Find it on the globe

Olm is there as a tiny animated figure that breathes and looks around. From far away the planet is only a blue ball; detail arrives as you zoom in, and this one appears once you are close enough. Open it on the globe.

It sits at its real coordinates, not near them — the same numbers listed in the facts above. Switch off the layer for this kind of place and it disappears again; the buttons for that are down the right-hand edge.