Reclaimed from the Recycle Bin, that’s what Issue #33 of this guide is about. Last week the beautiful, if a bit sinister Sea Swallow was in the spotlight before being thrown at some young Australian. This week a pale skinned, skinny waif of a thing boldly stumbles into the daylight from its underground home. Hope you enjoy.
Issue #33 Olm
Kingdom – Animalia
Phylum – Chordata
Class – Amphibia
Order – Caudata
Family – Proteidae
Genus – Proteus
Species – anguinus
Related Species - The genus Proteus is one (of two) found in the family Proteidae, the other is the genus Necturus which contains the five species of Mudpuppy (1)
A Baby Cave Dragon
The Olm is a pale, almost translucent, skinned cave salamander whose eel like body grows to a length of 40cm. Unusually the Olm stays in a neonatal or tadpole like stage, retaining juvenile features such as exposed gills and a lateral line. Olms have feathery red gills that are used in respiration alongside rudimentary lungs, although the majority of gas exchange takes place in water. While the Olm has eyes, they are covered by the skin and can only detect changes in light level. For navigation the species relies of its sense of smell, vibrations in the water and faint electrical currents in the water (2).
Like all amphibians the Olm is a carnivore, with insects and small crustaceans it’s preferred prey. Due to its slow metabolism however, the Olm rarely has to eat, with individuals going up to six years without food. While it has no predators within the caves it lives in, when flushed out by flash floods the Olm is fed upon by a wide range of animals including toads, water snakes, herons and large fish.
Olms are solitary throughout their entire lives except when they come together to breed. Fertilisation is assumed to be internal with eggs later being laid under stones on the cave floor. Juvenile Olms are similar to the adults save for functioning eyes and no legs, both features they gain at an age of four months. Despite being adults, the young Olms won’t be ready to breed until they are at least 14 years old due to the species slow metabolism, with an average lifespan of over 65 years.
Five Fun Olm Facts
The Genus Proteus is ancient with remains of Olm like animals dating back at least 30 million years
As recently as the 1600s, local people used to believe that Olms washed out of caves by flash floods were baby dragons
Even famed naturalist Charles Darwin had time to marvel at the Olms oddness. In his book the Origin of Species he describes the salamander thusly, “Far from feeling surprise that some of the cave-animals should be very anomalous...as is the case with blind Proteus with reference to the reptiles of Europe, I am only surprised that more wrecks of ancient life have not been preserved, owing to the less severe competition to which the scanty inhabitants of these dark abodes will have been exposed.” (3)
Very recently a race of dark skinned Olms, descendents of salamanders washed to the cave mouths perhaps, have appeared. These ‘Black Proteus’ have dark skin, working eyes and reduced limbs as adaptations to life in the light. (4)
The Olm is considered the poster species of cave biology and after 300 years of research still attracts much excitement from scientists. In Slovenia in particular, the species is popular with Proteus appearing on the 10 tolar coin and lending its name to the countries leading popular science magazine
1 - www.arkive.org
2 - Schegel P. & Bulog B. (1997). Population-specific behavioral electrosensitivity of the European blind cave salamander, Proteus anguinus. Journal of Physiology (Paris)91: 75–79
3 - Darwin C. (1859). On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life.
4 - Sket B. & Arntzen J.W. (1994). A black, non-troglomorphic amphibian from the karst of Slovenia: Proteus anguinus parkelj n. ssp (Urodela: Proteidae). Bijdragen tot de Dierkunde 64:33–53.
1 - http://upload.wikimedia.org/wikipedia/commons/f/f0/Proteus_anguinus_Postojnska_Jama_Slovenija.jpg
2 - http://www.showcaves.com/maps/Big/Proteus.png
3 - http://whitleyaward.org/wp-content/uploads/2010/12/Jana-Species_Proteus.jpg
4 - http://img.xcitefun.net/users/2011/03/233461,xcitefun-human-fish-1.jpg
And with that we bid adieu to the oddity known at the Olm as it slithers out of the spotlight. Next week we head to a ‘big island’ to look at a ‘small lizard’ who strikes fear into the locals. Until then comment, critique and check out the Bestiary of Past Issues.