The 5th episode of ‘Seven Worlds, One Planet’ airs today, focusing on Europe – a continent transformed by mankind. Sometimes, Europe’s crowded cities and intensive agriculture can make it seem devoid of unique wildlife. However, fascinating species can be found here, you just have to look a little closer. Take for example, an amphibian that lurks in the pitch black caves of Slovenia and Croatia. An animal that can live for over 100 years and survive for 10 years without food. When first discovered, they were thought to be the offspring of cave dragons…
This remarkable amphibian is known as the olm salamander (Proteus anguinus), or simply the olm. They are fully aquatic and swim through the water like an eel; the olm eats, sleeps and breeds underwater. Lacking skin pigmentation, they appear a pale pinkish-white colour. This strange creature has developed a range of adaptations to a life in darkness. For one, they have no developed eyes and are completely blind. Eyes aren’t much use when there’s no light around. Moreover, they keep their external gills throughout adulthood, similar to the axolotl.
To compensate for its lack of sight, the olm has enhanced its other senses, especially their smell and hearing. They have advanced chemoreceptors in their nasal cavity that allow them to detect even very low concentrations of organic compounds. This helps them when foraging for insects, small crustaceans and snails. In addition, their ears can receive sounds waves in the water and vibrations from the ground. They can even sense electrical and magnetic fields, although more research is needed to fully understand the abilities of the olm.
As I mentioned earlier, the olm can go a decade without food. This is possible because they can consume large amounts of food at once. This nutrients is then stored in the liver. When food becomes scarce, the olm salamander reduces its activity and metabolic rate – they may even begin to reabsorb their own body tissues.
The olm’s adaptations specific to its unique habitat make it highly vulnerable to changes in the environment. For instance, chemical pollutants flooding into their caves break down into toxic compounds that can kill these salamanders if in high enough concentrations. They are also threatened by black market collectors. This is because their popularity has risen and the fact that they can be found nowhere else on earth. The olm has called the caves of Slovenia and Croatia home for 20 million years. These caves were once a tranquil sanctuary for them but it is no longer free from our severe and far-reaching impacts on this planet.
Hennessy, K., Wiggins, V. (2014) Animal Encyclopedia: The Definitive Visual Guide. 2nd edn. London. Dorling Kindersley.
Seven Worlds, One Planet Trailer: https://www.youtube.com/watch?v=nm5XasUl7HM