The Dragon of Vrhnika – The Olm
I've just got back from the caves of Postojna in Slovenia having spent a couple of weeks filming an animal that I've wanted to meet for a long time; the film is part of the second series of "Nick Baker's Weird Creatures" which if you live in the UK you may well have caught when it premiered before christmas those of you with animal Planet it is going out as we speak.
This month's featured creature is an animal so bizarre that I couldn't help but give you a little taster of what's to come.
The Olm has intrigued me for many years – it’s an animal that defines the word odd. These anaemic looking salamanders live in the darkest places on earth for their entire lives, living in the subterranean world of the cave systems of the Dinaric Karst region of Europe namely the countries that border the eastern coast of the Adriatic sea, from Trieste in Italy all the way down to Herzegovina.
These weird amphibians gave rise to the legends of great dragons living deep below the surface in their grotto’s as occasionally heavy rains would wash these skinny slithers of amphibian life from their normal habitat up to the surface. Being naturally a pinkish white (due to the pigment of their red blood showing through their semi opaque skin) and with no obvious developed eyes to speak of they really do look like a work in progress, like an aborted embryo.
It was the perfect adventure to go looking for these animals as not only are they peculiar but they are obligate cave dwellers living in a highly specialised environment, this has over time created a very unique creature, with no close relatives this side of the Atlantic and a bit of cool folklore thrown in to boot it just caught my imagination perfectly and what is more there is a twist in the Olm’s tail too.
So what is an Olm?
Well it is an amphibian of which we have 45 species here in Europe of these about 20 belong to the group of tailed amphibians that we call newts or salamanders (a newt is a kind of salamander).
The Olm (Proteus anguinus) is the only one of its kind in Europe; it's nearest relative is the Mud Puppy (Necturus sp.) from the eastern USA and although this amphibian is also totally aquatic it lives in the surface water, a world of light that is familar to us. Here sunlight means that the sense of sight can be utilised by most creatures and in this world eye's rule. Someting that cannot be said for the Olm deep within the black guts of the earth.
So, as we understand it a long time ago a mud puppy like creature started to live in the cave systems and whereas its relatives on the surface have long since disappeared from Europe, deep within the fissures of the Dinaric Karstland the Olm has continued to live out its very private life.
Here in the dark, cool subterranean waters the Olm has become ecologically trapped. It has become so highly modifiied to survive the constant but demanding conditions it's particular life style places upon it that it could live nowhere else. So here it has remained, locked away in the cellar, forgotten about, a ghostly relic of a time that was.
Look at the pictures of an Olm and several things strike you as being different to most of the other Salamanders that you may have seen. For a start the most obvious thing that stands out; is it's white colour, this is not really a "colour" but a lack of it.
The Olm has no pigment in its skin and so as a consequence they appear this very pale and pallid pink or yellow. The pink is simply the colour of the blood in its vessels showing through the skin and the yellow is a natural pigment in the cells called Riboflavin. When I was hunting for Olm’s in the underground pools and ponds; this pale, almost ghost like pallor made them stand out from their background, but because they didn't much like the light from out torches they would slowly drift off into the cracks and crevices between the rocks or into deep water, looking a bit like a torn shred of satin being dragged along the bottom.
The other thing that you will notice in the close up shots in particular are the both the lack of eyes and the presence of gills. Let's start with the gills, these are the frilly pinkish things that waft around on the sides of the Olm's head, just like in fish these gills have the job of extracting useful oxygen from the water. If there is lots of dissolved oxygen in the water then the gills are not so flouncy if it is scarce the Olm needs a greater surface area and so the gills appear "fluffier".
"The Olm has chosen between Extinction and another kind of Oblivion"
All salamanders at some point in their life have external gills like these; it is simply part of growing up. Salamanders like frogs have a tadpole stage in their life-cycle too and as they grow and get their full quota of legs just like frog and toad tadpoles they absorb the gills and metamorphose into the adult form.
Now the Olm like a few other salamanders like the Mud puppy and the word famous lab animal the Axolotl from Mexico exhibit something called Neoteny; they keep their juvenile characteristics into their adulthood. Why? Well nobody knows for sure but it probably has a lot to do with the fact that the conditions in the underground water are very stable; the temperature is fairly constant, and also there is a distinct lack of predators.
The eyes well they have atrophied to the point where they do not see well at all, skin has grown over where the eyes should be, have a good look at some of the Olm portraits here and you can just about make out a dark dot. There isn't much call for eyes down there in the caves, there is no light and eyes are expensive organs to have if you don't need them.
Now try and imagine what its like with no light, down there under the ground; it's difficult isn't it! Because we are such visual monkeys ourselves even if we try and imagine a cave in the pitch black we still have to turn a light on in our minds in order to see what it should be like! So how does an Olm not only find its way around but more to the point how does it meet other Olms and let's not forget it's a predator too, so how does it catch its food?
Well it may not have any eyes but our Troglodyte is a very sensitive little salamander. Its whole body is very perceptive to vibration;
all along its flanks are various vibration sensitive organs (these mechanoreceptors are very similar to a fishes lateral line) the Olm also has a very large "crystal mass" in its inner ear so although it doesn’t have any external ears (sticky out bits that you and I associate with these organs) it can pick up sound in the form of vibration, in fact this part of its body is much more highly developed than any other salamander. There are many taste cells on the body too, concentrated around the head. We all know that sharks can detect the tiny electric charges produced by all living cells, this allows them to detect the position of their prey even in low visibility conditions, well the same sense is shared by the Olm, and is possibly the reason why the White Olm has such a curious flattened almost shovel shaped head on the underside it is furnished with a high concentration of ampullae, capable of detecting these minute electric charges.
I found it strange also to learn of this animal's extreme sensitivity to light; something I witnessed first hand in the water filled labyrinthine world that I shared with this animal for just a few days this past June. Just shining a very dim red light emitted by an L.E.D was enough to send this animal fleeing; although in a slow and laboured fashion as is fitting for an animal that is on a very tight energetic budget. Why would an animal confined to the dark even need to be sensitive to the light? Well I guess this must come down to the survival fact that on the surface an Olm that was washed out of the cave system wouldn’t last very long, so a natural survival strategy would be for it to be able to head back into the dark - in order to do this the Olm needs to be a able to tell the two apart.
A few things worth knowing about Olms...
- They grow to about 25-20cm in length
- They have three digits on the front feet and two the back
- They are still capable of breeding when 30-40 years old
- Some individuals are known to be over sixty years old (they count the growth rings in their bones - just like those found in tree trunks)
- They are rumoured to live as long as 100 plus years; whatever the actual fact they owe their relatively large number of years to the very slow metabolism, a design feature essential if you live in a very resource poor environment i.e. there isn't a huge amount of food where they live.
- They have been recorded going without food for over six years - this could be simple down to their ability to slow down metabolism and respond to starvation by entering a kind of torpor or it has been suggested that microscopic bacterial life lives on its slime coated skin and when it moults (as all amphibians do) it eats and recycles not only its skin but the sticky "lawn" of bacteria that have bee growing on it!
- The Olm is the only and therefore the largest totally troglodytic vertebrate!
- Recent genetic works suggests there may be at least 6 different species of Olm
- Many of the different populations of White Olm are more genetically distinct from each other than the White Olm are from the Black Olm - suggesting different races probably that became isolated from each other some 5-9 million years ago before the Karst formation took place.
- White Olm exposed to light develop dark pigment; although they never develop useful eyes.
It was there at the beginning..
The White Olm was first described in literature in Slovenia by Baron Janez Valvasor in his book "The Glory of the Duchy of Carniola" published in 1689 here he collected local folklore as well as actual observations and blended them together in a kind of "best fit". Here the Olm tale is told by locals interviewed by Valvasor who describe it as a baby dragon. "Barely a span long, akin to a lizard, in short, a worm and vermin of which there are many hereabouts". It wasn't until a physician and naturalist called Giovanni Scopoli had some specimens sent to him that the world at large started to hear about the Olm. To cut a long story short he got very excited as he had never seen an animal like this before and he sent specimens to all his learned friends and biologists. The great Carl Linnaeus even got one, but even he though it was a juvenile something and he wouldn’t describe it as a species as (and rightfully at the time) until he had seen it turn into its adult form (Neoteny in Salamanders as not really a well known phenomena back then). Then one of Scopoli's specimens was pulled off a shelf in Vienna by Zoologist, who before Scopoli had made known his discovery to the scientific world beat him to it. Dr Laurenti named the Olm in 1768 although he was a little inaccurate in his description he even suggested it came form the lakes and not the caves. So although Proteus was finally described to the scientific world it wasn’t actually linked to the caves until much later.
"Barely a span long, akin to a lizard, in short, a worm and vermin of which there are many hereabouts"
Even though it was the first troglodytic animal ever described it didn’t count as such and was in turn beaten to the number one spot, officially by the Narrow-necked beetle! (There's a picture of one in the Gallery that accompanies this adventure and it's a real 'super star' of Speleobiology). But however you look at it the birth of Speleobiology (the study of cave life), the Olm and Slovenia are all inextricably tied up together.
A Living Icon...
It was in Slovenia that the Olm was first described and so the country and the animal will forever be linked. It seems that the tiny country of Slovenia - struggling for an identity within the E.U has almost chosen the Olm as a emblem and an ICON and this is reflected in images of this strange subterranean salamander almost everywhere you look; on posters, tea towels, mugs, T-shirts, chocolate Olms and even images of them set into the concrete supports pillars of my "eastern block" hotel accommodation and on the old door handles to the Postonja cave entrance. The Slovenia forestry department have it as part of their logo too.
I guess what I think is rather special is that such a very obscure animal, that is rarely seen has become raised on a pedestal of popularity and this little pale slip of an animal that represents one of the most challenging ways of life in a dark and dingy world is famous - certainly among the people of Slovenia. It's nice that these people really seem to love their odd little salamander.
Strange creature, strange name
The Olm is known by many other names; the locals call it the "human fish" because of its weird almost human coloured complexion, although obviously the word fish is used loosely to describe a creature that lives in the water, I even heard the recently discovered, sub-species of Olm; the Black Olm referred to by the locals as the "black fish". In Slovenian it is called the Mocheril.
The Latin name of this animal tells of a story too; Proteus anguinus - Proteus was Poseidon's servant and keeper of the sea creatures in Greek myth and Anguinus which means snake like.
Can you help me get to the bottom of this?
The name English name for this creature Olm intrigues me, but can I find out its origin? No I can't. I was originally told that it is a totally made up name, sort of non-sense. Apparently the word Mol means amphibian or newt or something like that in German, but I cannot find any reference to this. The idea was that a German biologist just rearranged the letters to form an anagram and so Olm was created. It’s a great story. Maybe the language reference is wrong? If you can help please drop me a line on the forum.
"What's black without white? What's dark without light?" - It's just too perfect a story.
To top of this section nicely and just when you think and the scientific world thought they understood a little bit about the white Olms from the black caves came a surprising discovery... In 1986 A black salamander looking a little bit like an Olm was found by a Geologist pumping water form a spring. Where? Well where else than the White Carniola region of Slovenia! He fortunately recognised it as being a little bizarre and showed it to a biologist who knew about these things and so the Black Olm was discovered (Proteus anguinus parkelj) a sub-species of the White Olm .
What's really weird is that the black Olm comes to the surface nearly always at night appearing from just a few springs, it has the sorts of eyes you would almost expect from a salamander its size – so it can see. It also has a less flattened head and a shorter jaw than its pale cousin. It is such a new and exciting discovery that they are heavily guarded; the springs from which they surface look more like fort Knox than a site of great herpetological interest, surrounded by razor wire and locked iron grids
What's exciting for me though is the fact that we know next to nothing about these animals. Sure the scientific community has poked and prodded them and we know what a Black Olm it is if we wanted to physically describe it to someone.
But we actually know nothing about the animal itself. Staring through the iron grid at these black very lean and stringy amphibians I couldn't help but reflect on the fact that sixty years of so ago, before this animal was even known to science this individual was spawned somewhere below me, possibly hundreds of metres down in the cool waters that emanate from the depths of the earth, somewhere no human has been and quite possibly will never see. There is something about an enigma like that which makes this situation so delicious - a small black slip of life that we can only guess at, it kind of makes me feel humble and puts us as a species in our place.