The olm or proteus (''Proteus anguinus'') is an aquatic
salamander
Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten ...
in the family
Proteidae
The family Proteidae is a group of aquatic salamanders found today in the Balkan Peninsula and North America. The range of the genus ''Necturus'' (commonly known as waterdogs or mudpuppies) runs from southern central Canada, through the midwes ...
, the only
exclusively cave-dwelling chordate
A chordate () is an animal of the phylum Chordata (). All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These fiv ...
species found in Europe. In contrast to most
amphibian
Amphibians are tetrapod, four-limbed and ectothermic vertebrates of the Class (biology), class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terres ...
s, it is entirely
aquatic, eating, sleeping, and breeding underwater. Living in caves found in the
Dinaric Alps
The Dinaric Alps (), also Dinarides, are a mountain range in Southern and Southcentral Europe, separating the continental Balkan Peninsula from the Adriatic Sea. They stretch from Italy in the northwest through Slovenia, Croatia, Bosnia and Herz ...
, it is
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to the waters that flow underground through the extensive limestone bedrock of the
karst
Karst is a topography formed from the dissolution of soluble rocks such as limestone, dolomite, and gypsum. It is characterized by underground drainage systems with sinkholes and caves. It has also been documented for more weathering-resistant ro ...
of Central and Southeastern Europe in the basin of the
Soča
The Soča ( in Slovene) or Isonzo ( in Italian; other names fur, Lusinç, german: Sontig, la, Aesontius or ') is a long river that flows through western Slovenia () and northeastern Italy ().
An Alpine river in character, its source lies in ...
River ( it, Isonzo) near
Trieste
Trieste ( , ; sl, Trst ; german: Triest ) is a city and seaport in northeastern Italy. It is the capital city, and largest city, of the autonomous region of Friuli Venezia Giulia, one of two autonomous regions which are not subdivided into provi ...
, Italy, southwestern
Croatia
, image_flag = Flag of Croatia.svg
, image_coat = Coat of arms of Croatia.svg
, anthem = "Lijepa naša domovino"("Our Beautiful Homeland")
, image_map =
, map_caption =
, capit ...
, and
Bosnia and Herzegovina
Bosnia and Herzegovina ( sh, / , ), abbreviated BiH () or B&H, sometimes called Bosnia–Herzegovina and often known informally as Bosnia, is a country at the crossroads of south and southeast Europe, located in the Balkans. Bosnia and H ...
.
Introduced populations are found near
Vicenza
Vicenza ( , ; ) is a city in northeastern Italy. It is in the Veneto region at the northern base of the ''Monte Berico'', where it straddles the Bacchiglione River. Vicenza is approximately west of Venice and east of Milan.
Vicenza is a th ...
, Italy, and
Kranj
Kranj (, german: Krainburg) is the third-largest city in Slovenia, with a population of 37,941 (2020). It is located approximately northwest of Ljubljana. The centre of the City Municipality of Kranj and of the traditional region of Upper Carniol ...
,
Slovenia
Slovenia ( ; sl, Slovenija ), officially the Republic of Slovenia (Slovene: , abbr.: ''RS''), is a country in Central Europe. It is bordered by Italy to the west, Austria to the north, Hungary to the northeast, Croatia to the southeast, an ...
.
It is also called the "human fish" by locals because of its fleshy skin color (translated literally from sl, človeška ribica, mk, човечка рипка, hr, čovječja ribica, bs, čovječja ribica sr, човечја рибица), as well as "cave salamander" or "white salamander".
In Slovenia, it is called ''močeril'' (from *''močerъ'' 'earthworm, damp creepy-crawly'; ''moča'' 'dampness'). It was first mentioned in 1689 by the local
naturalist Valvasor
Johann Weikhard Freiherr von Valvasor or Johann Weichard Freiherr von Valvasor ( sl, Janez Vajkard Valvasor, ) or simply Valvasor (baptised on 28 May 1641 – September or October 1693) was a natural historian and polymath from Carniola, p ...
in his ''
Glory of the Duchy of Carniola'', who reported that, after heavy rains, the olms were washed up from the underground waters and were believed by local people to be a cave
dragon
A dragon is a reptilian legendary creature that appears in the folklore of many cultures worldwide. Beliefs about dragons vary considerably through regions, but dragons in western cultures since the High Middle Ages have often been depicted as ...
's offspring.
This
cave salamander
A cave salamander is a type of salamander that primarily or exclusively inhabits caves, a group that includes several species. Some of these animals have developed special, even extreme, adaptations to their subterranean environments. Some specie ...
is most notable for its adaptations to a life of complete darkness in its underground habitat. The olm's
eye
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
s are
undeveloped
A developing country is a sovereign state with a lesser developed industrial base and a lower Human Development Index (HDI) relative to other countries. However, this definition is not universally agreed upon. There is also no clear agreem ...
, leaving it blind, while its other
sense
A sense is a biological system used by an organism for sensation, the process of gathering information about the world through the detection of Stimulus (physiology), stimuli. (For example, in the human body, the brain which is part of the cen ...
s, particularly those of
smell and
hearing
Hearing, or auditory perception, is the ability to perceive sounds
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psycholog ...
, are acutely developed. It also lacks any
pigmentation
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...
in its
skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other cuticle, animal coverings, such as the arthropod exoskeleton, have diffe ...
. It has three toes on its forelimbs, but only two toes on its hind feet. It exhibits
neoteny
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...
, retaining
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
l characteristics like external
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...
s into adulthood,
like some American amphibians, the
axolotl
The axolotl (; from nci, āxōlōtl ), ''Ambystoma mexicanum'', is a paedomorphic salamander closely related to the tiger salamander. Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis. Instea ...
and the mudpuppies (''
Necturus
''Necturus'' is a genus of aquatic salamanders native to the eastern United States and Canada. They are commonly known as waterdogs and mudpuppies. The common mudpuppy ''(N. maculosus)'' is probably the best-known species – as an amphibian wi ...
''). The olm is the only
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
in the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Proteus'' and the only European species of the
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Proteidae
The family Proteidae is a group of aquatic salamanders found today in the Balkan Peninsula and North America. The range of the genus ''Necturus'' (commonly known as waterdogs or mudpuppies) runs from southern central Canada, through the midwes ...
, whose other extant genus is ''Necturus''.
Etymology
The word ''olm'' is a
German
German(s) may refer to:
* Germany (of or related to)
**Germania (historical use)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizens of Germany, see also German nationality law
**Ger ...
loanword
A loanword (also loan word or loan-word) is a word at least partly assimilated from one language (the donor language) into another language. This is in contrast to cognates, which are words in two or more languages that are similar because th ...
that was incorporated into English in the late 19th century. The origin of the German original, or 'cave olm', is unclear.
It may be a variant of the word 'salamander'.
Description
External appearance
![Protée aveugle](https://upload.wikimedia.org/wikipedia/commons/1/1f/Prot%C3%A9e_aveugle.jpg)
The olm's body is
snake
Snakes are elongated, Limbless vertebrate, limbless, carnivore, carnivorous reptiles of the suborder Serpentes . Like all other Squamata, squamates, snakes are ectothermic, amniote vertebrates covered in overlapping Scale (zoology), scales. Ma ...
like, long, with some specimens reaching up to .
[Weber A. (2000). ''Fish and amphibia''. In: Culver D.C. ''et al.'' (ed.): ''Ecosystems of the world: Subterranean Ecosystems'', pp. 109–132. Amsterdam: ]Elsevier
Elsevier () is a Dutch academic publishing company specializing in scientific, technical, and medical content. Its products include journals such as ''The Lancet'', ''Cell'', the ScienceDirect collection of electronic journals, '' Trends'', th ...
The average length is between 23-25 cm.
Females grow larger than males, but otherwise the primary external difference between the sexes is in the
cloaca
In animal anatomy, a cloaca ( ), plural cloacae ( or ), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles and birds, a ...
region (shape and size) when breeding.
The trunk is cylindrical, uniformly thick, and segmented with regularly spaced furrows at the
myomere
Myomeres are blocks of skeletal muscle tissue arranged in sequence, commonly found in aquatic chordates. Myomeres are separated from adjacent myomeres by connective fascia (myosepta) and most easily seen in larval fishes or in the olm. Myomere ...
borders. The
tail
The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...
is relatively short, laterally flattened, and surrounded by a thin fin. The limbs are small and thin, with a reduced number of digits compared to other amphibians: the front legs have three digits instead of the normal four, and the rear have two digits instead of five. Its body is covered by a thin layer of skin, which contains very little of the
pigment
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...
riboflavin
Riboflavin, also known as vitamin B2, is a vitamin found in food and sold as a dietary supplement. It is essential to the formation of two major coenzymes, flavin mononucleotide and flavin adenine dinucleotide. These coenzymes are involved in ...
, making it yellowish-white or pink in color.
The white skin color of the olm retains the ability to produce
melanin
Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...
, and will gradually turn dark when exposed to light; in some cases the
larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
The ...
e are also colored. Its pear-shaped head ends with a short, dorsoventrally flattened snout. The mouth opening is small, with tiny
teeth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tear ...
forming a
sieve
A sieve, fine mesh strainer, or sift, is a device for separating wanted elements from unwanted material or for controlling the particle size distribution of a sample, using a screen such as a woven mesh or net or perforated sheet material. T ...
to keep larger particles inside the mouth. The nostrils are so small as to be imperceptible, but are placed somewhat
laterally near the end of the snout. The regressed
eye
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...
s are covered by a layer of skin. The olm breathes with external
gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...
s that form two branched tufts at the back of the head.
They are red in color because the oxygen-rich
blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the c ...
shows through the non-pigmented skin. The olm also has rudimentary
lung
The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of t ...
s, but their role in respiration is only accessory, except during
hypoxic
Hypoxia means a lower than normal level of oxygen, and may refer to:
Reduced or insufficient oxygen
* Hypoxia (environmental), abnormally low oxygen content of the specific environment
* Hypoxia (medical), abnormally low level of oxygen in the tis ...
conditions.
Sensory organs
Cave-dwelling animals have been prompted, among other adaptations, to develop and improve non-visual sensory systems in order to orient in and adapt to permanently dark habitats.
The olm's sensory system is also adapted to life in the subterranean aquatic environment. Unable to use vision for orientation, the olm compensates with other senses, which are better developed than in amphibians living on the surface. It retains larval proportions, like a long, slender body and a large, flattened head, and is thus able to carry a larger number of
sensory receptor
Sensory neurons, also known as afferent neurons, are neurons in the nervous system, that convert a specific type of stimulus, via their receptors, into action potentials or graded potentials. This process is called sensory transduction. The cell ...
s.
Photoreceptors
Although blind, the olm swims away from light. The eyes are regressed, but retain sensitivity. They lie deep below the
dermis of the skin and are rarely visible except in some younger adults. Larvae have normal eyes, but development soon stops and they start regressing, finally atrophying after four months of development.
The
pineal body
The pineal gland, conarium, or epiphysis cerebri, is a small endocrine gland in the brain of most vertebrates. The pineal gland produces melatonin, a serotonin-derived hormone which modulates sleep patterns in both circadian and seasonal cycle ...
also has photoreceptive cells which, though regressed, retain visual pigment like the photoreceptive cells of the regressed eye. The pineal gland in ''Proteus'' probably possesses some control over the physiological processes.
[Langecker T.G. (2000). ''The effects of continuous darkness on cave ecology and cavernicolous evolution''. In: Culver D.C. ''et al.'' (eds.): ''Ecosystems of the world: Subterranean Ecosystems'', pp. 135–157. Amsterdam: Elsevier] Behavioral
Behavior (American English) or behaviour (British English) is the range of actions and mannerisms made by individuals, organisms, systems or artificial entities in some environment. These systems can include other systems or organisms as well ...
experiments revealed that the skin itself is also sensitive to light.
Photosensitivity of the integument is due to the pigment
melanopsin
Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene ''Opn4''. In the mammalian retina, there are two additional categories of opsins, both involved in the for ...
inside specialized cells called
melanophore
Chromatophores are cells that produce color, of which many types are pigment-containing cells, or groups of cells, found in a wide range of animals including amphibians, fish, reptiles, crustaceans and cephalopods. Mammals and birds, in contrast, ...
s. Preliminary immunocytochemical analyses support the existence of photosensitive pigment also in the animal's integument.
[Kos M. (2000). (''Immunocitochemical analysis of the visual pigments in the sensory cells of the eye and the pineal organ of the olm (Proteus anguinus, Amphibia, Urodela).'') PhD thesis. Ljubljana: ]University of Ljubljana
The University of Ljubljana ( sl, Univerza v Ljubljani, , la, Universitas Labacensis), often referred to as UL, is the oldest and largest university in Slovenia. It has approximately 39,000 enrolled students.
History Beginnings
Although certain ...
.
Chemoreceptors
The olm is capable of sensing very low concentrations of organic compounds in the water. They are better at sensing both the quantity and quality of prey by smell than related amphibians.
[Hüpop K. (2000). ''How do cave animals cope with the food scarcity in caves?''. In: Culver D.C. ''et al.'' (ed.): ''Ecosystems of the world: Subterranean Ecosystems'', pp. 159–188. Amsterdam: Elsevier] The nasal
epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
, located on the inner surface of the nasal cavity and in the
Jacobson's organ
The vomeronasal organ (VNO), or Jacobson's organ, is the paired auxiliary olfactory (smell) sense organ located in the soft tissue of the nasal septum, in the nasal cavity just above the roof of the mouth (the hard palate) in various tetrapods. T ...
, is thicker than in other amphibians.
The
taste buds
Taste buds contain the taste receptor cells, which are also known as gustatory cells. The taste receptors are located around the small structures known as papillae found on the upper surface of the tongue, soft palate, upper esophagus, the che ...
are in the
mucous
Mucus ( ) is a slippery aqueous secretion produced by, and covering, mucous membranes. It is typically produced from cells found in mucous glands, although it may also originate from mixed glands, which contain both serous and mucous cells. It is ...
epithelium of the mouth, most of them on the upper side of the
tongue
The tongue is a muscular organ (anatomy), organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive system, digestive process, and is the primary organ of taste. The tongue's upper surfa ...
and on the entrance to the gill cavities. Those in the oral cavity are used for tasting food, where those near the gills probably sense chemicals in the surrounding water.
Mechano- and electroreceptors
The sensory
epithelia
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellula ...
of the
inner ear
The inner ear (internal ear, auris interna) is the innermost part of the vertebrate ear. In vertebrates, the inner ear is mainly responsible for sound detection and balance. In mammals, it consists of the bony labyrinth, a hollow cavity in the ...
are very specifically differentiated, enabling the olm to receive
sound
In physics, sound is a vibration that propagates as an acoustic wave, through a transmission medium such as a gas, liquid or solid.
In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...
waves in the water, as well as
vibration
Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic function, periodic, such as the motion of a pendulum ...
s from the ground. The complex functional-morphological orientation of the sensory cells enables the animal to register the sound sources.
[Bulog B. (1990). (''Sense organs of the octavolateral system in proteus Proteus anguinus (Urodela, Amphibia). I. Otic labyrinth''). Biološki vestnik 38: 1–16 ] As this animal stays
neotenic
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...
throughout its long life span, it is only occasionally exposed to normal adult hearing in air, which is probably also possible for Proteus as in most salamanders. Hence, it would be of adaptive value in caves, with no vision available, to profit from underwater hearing by recognizing particular sounds and eventual localization of prey or other sound sources, i.e. acoustical orientation in general. The ethological experiments indicate that the best hearing sensitivity of ''Proteus'' is between 10 Hz and up to 15,000 Hz.
[Bulog B. & Schlegel P. (2000). ''Functional morphology of the inner ear and underwater audiograms of Proteus anguinus (Amphibia, Urodela)''. Pflügers Arch 439(3), suppl., pp. R165–R167.] The
lateral line
The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial ...
supplements inner ear sensitivity by registering low-frequency nearby water displacements.
A new type of
electroreception
Electroreception and electrogenesis are the closely-related biological abilities to perceive electrical stimuli and to generate electric fields. Both are used to locate prey; stronger electric discharges are used in a few groups of fishes to stu ...
sensory organ has been analyzed on the head of ''Proteus'', utilizing light and
electron microscopy
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a hi ...
. These new organs have been described as
ampullary organs.
Like some other lower
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, ...
s, the olm has the ability to register weak
electric field
An electric field (sometimes E-field) is the physical field that surrounds electrically charged particles and exerts force on all other charged particles in the field, either attracting or repelling them. It also refers to the physical field fo ...
s.
Some behavioral experiments suggest that the olm may be able to use Earth's
magnetic field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
to orient itself. In 2002, ''Proteus'' ''anguinus'' was found to align itself with natural and artificially modified magnetic fields.
Ecology and life history
The olm swims by serpentine bending of the body.
The olm lives in well-oxygenated underground waters with a typical, very stable temperature of , infrequently as warm as .
The black olm may occur in surface waters that are somewhat warmer.
At a temperature of , the olm's
embryo
An embryo is an initial stage of development of a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male spe ...
nic development (time in the eggs before hatching) is 140 days, but it is somewhat slower in colder water and faster in warmer, being as little as 86 days at . After hatching, it takes another 14 years to reach sexual maturity if living in water that is .
The larvae gain adult appearance after nearly four months, with the duration of development strongly correlating with water temperature.
Unconfirmed historical observations of
viviparity
Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...
exist, but it has been shown that the females possess a
gland
In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland).
Structure
De ...
that produces the egg casing, similar to those of
fish
Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
and egg-laying amphibians.
[Aljančič M., Bulog B. et al. (1993). ''Proteus – mysterious ruler of Karst darkness''. Ljubljana: Vitrium d.o.o. ] Paul Kammerer
Paul Kammerer (17 August 1880, in Vienna – 23 September 1926, in Puchberg am Schneeberg) was an Austrian biologist who studied and advocated Lamarckism, the theory that organisms may pass to their offspring characteristics acquired in their lif ...
reported that female olm gave birth to live young in water at or below and laid eggs at higher, but rigorous observations have not confirmed that. The olm appears to be exclusively
oviparous
Oviparous animals are animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive method of most fish, amphibians, most reptiles, and all pterosaurs, dinosaurs (including birds), and ...
.
The female lays up to 70 eggs, each about in diameter, and places them between rocks, where they remain under her protection.
[Aljančič G. and Aljančič M. (1998). (''The animal of the month of October: olm''). Proteus 61(2): 83–87 ] The average is 35 eggs and the adult female typically breeds every 12.5 years.
The tadpoles are long when they hatch and live on
yolk
Among animals which produce eggs, the yolk (; also known as the vitellus) is the nutrient-bearing portion of the egg whose primary function is to supply food for the development of the embryo. Some types of egg contain no yolk, for example bec ...
stored in the cells of the digestive tract for a month.
Development of the olm and other
troglobite
A troglobite (or, formally, troglobiont) is an animal species, or population of a species, strictly bound to underground habitats, such as caves. These are separate from species that mainly live in above-ground habitats but are also able to live u ...
amphibians is characterized by
heterochrony
In evolutionary developmental biology, heterochrony is any genetically controlled difference in the timing, rate, or duration of a developmental process in an organism compared to its ancestors or other organisms. This leads to changes in the si ...
– the animal does not undergo
metamorphosis
Metamorphosis is a biological process by which an animal physically develops including birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation. Some inse ...
and instead retains larval features. The form of heterochrony in the olm is
neoteny
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared ...
– delayed
somatic
Somatic may refer to:
* Somatic (biology), referring to the cells of the body in contrast to the germ line cells
** Somatic cell, a non-gametic cell in a multicellular organism
* Somatic nervous system, the portion of the vertebrate nervous sys ...
maturity with precocious reproductive maturity, i.e. reproductive maturity is reached while retaining the larval external
morphology
Morphology, from the Greek and meaning "study of shape", may refer to:
Disciplines
* Morphology (archaeology), study of the shapes or forms of artifacts
* Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
. In other amphibians, the metamorphosis is regulated by the
hormone
A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required ...
thyroxine
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4
rect 376 268 820 433 Thyroid-stimulating hormone
rect 411 200 849 266 Thyrotropin-releasing hormone
rect 297 168 502 200 Hypothalamus
rect 66 216 386 25 ...
, secreted by the
thyroid
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...
gland. The thyroid is normally developed and functioning in the olm, so the lack of metamorphosis is due to the unresponsiveness of key
tissues to thyroxine.
The olm swims by eel-like twisting of its body, assisted only slightly by its poorly developed legs. It is a
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
y animal, feeding on small
crustacean
Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
s (for example, ''
Troglocaris
''Troglocaris'' is a genus of freshwater shrimp in the family Atyidae. These stygobitic, whitish and eyeless shrimp are found in Southern Europe (Dinaric Alps and West Caucasus). Although locally very common, the small ranges of the individual ...
'' shrimp, ''
Niphargus
''Niphargus'' is by far the largest genus of its family, the Niphargidae, and the largest of all freshwater amphipod genera.
Usually, these animals inhabit caves or groundwater. They occur in western Eurasia, in regions that were not covered by ...
'', ''
Asellus
''Asellus'' is a genus of isopod crustaceans in the family Asellidae.
Species
Asellus is divided into three subgenera which contain the following species:
Asellus Geoffroy, 1764
*'' Asellus alaskensis'' Bowman & Holmquist, 1975https://biostor ...
'' and ''Synurella'' amphipods and ''
Oniscus asellus
''Oniscus asellus'', the common woodlouse, is one of the largest and most common species of woodlouse in the British Isles and Western and Northern Europe, growing to lengths of 16 mm and widths of 6 mm.
Distribution
The common woodlou ...
''),
snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastro ...
s (for example, ''
Belgrandiella'') and occasionally
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s and insect larvae (for example,
Trichoptera
The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the b ...
,
Ephemeroptera,
Plecoptera
Plecoptera is an order of insects, commonly known as stoneflies. Some 3,500 species are described worldwide, with new species still being discovered. Stoneflies are found worldwide, except Antarctica. Stoneflies are believed to be one of the mo ...
and
Diptera
Flies are insects of the order Diptera, the name being derived from the Greek δι- ''di-'' "two", and πτερόν ''pteron'' "wing". Insects of this order use only a single pair of wings to fly, the hindwings having evolved into advanced ...
).
It does not chew its food, instead swallowing it whole. The olm is resistant to long-term starvation, an adaptation to its underground habitat. It can consume large amounts of food at once, and store nutrients as large deposits of
lipid
Lipids are a broad group of naturally-occurring molecules which includes fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include ...
s and
glycogen
Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. The polysaccharide structure represents the main storage form of glucose in the body.
Glycogen functions as one o ...
in the
liver
The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...
. When food is scarce, it reduces its activity and
metabolic rate
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
, and can also reabsorb its own tissues in severe cases. Controlled experiments have shown that an olm can survive up to 10 years without food.
[Bulog B. (1994). (''Two decades of functional-morphological research on the olm (Proteus anguinus, Amphibia, Caudata'')). Acta Carsologica XXIII/19. ]
Olms are
gregarious
Sociality is the degree to which individuals in an animal population tend to associate in social groups (gregariousness) and form cooperative societies.
Sociality is a survival response to evolutionary pressures. For example, when a mother wasp ...
, and usually aggregate either under stones or in fissures.
Sexually active males are an exception, establishing and defending territories where they attract females. The scarcity of food makes fighting energetically costly, so encounters between males usually only involve
display
Display may refer to:
Technology
* Display device, output device for presenting information, including:
** Cathode ray tube, video display that provides a quality picture, but can be very heavy and deep
** Electronic visual display, output devi ...
. This is a behavioral adaptation to life underground.
Breeding
Reproduction has only been observed in captivity so far.
Sexually mature males have swollen cloacas, brighter skin color, two lines at the side of the tail, and slightly curled fins. No such changes have been observed in the females. The male can start courtship even without the presence of a female. He chases other males away from the chosen area, and may then secrete a female-attracting
pheromone
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
. When the female approaches, he starts to circle around her and fan her with his tail. Then he starts to touch the female's body with his snout, and the female touches his cloaca with her snout. At that point, he starts to move forward with a twitching motion, and the female follows. He then deposits the
spermatophore
A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa created by males of various animal species, especially salamanders and arthropods, and transferred in entirety to the female's ovipore during reproduction. Spermatophores ...
, and the animals keep moving forward until the female hits it with her cloaca, after which she stops and stands still. The spermatophore sticks to her and the
sperm
Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...
cells swim inside her cloaca, where they attempt to fertilize her eggs. The courtship ritual can be repeated several times over a couple of hours.
Longevity is estimated at up to 58 years. A study published in ''
Biology Letters
''Biology Letters'' is a peer-reviewed, biological, scientific journal published by the Royal Society. It focuses on the rapid publication of short high quality research articles, reviews and opinion pieces across the biological sciences. ''Biol ...
'' estimated that they have a maximum lifespan of over 100 years and that the lifespan of an average adult is around 68.5 years. When compared to the longevity and body mass of other amphibians, olms are
outlier
In statistics, an outlier is a data point that differs significantly from other observations. An outlier may be due to a variability in the measurement, an indication of novel data, or it may be the result of experimental error; the latter are ...
s, living longer than would be predicted from their size.
[
]
Taxonomic history
Olms from different cave systems differ substantially in body measurements, color and some microscopic characteristics. Earlier researchers used these differences to support the division into five species, while modern herpetologists understand that external morphology is not reliable for amphibian systematics and can be extremely variable, depending on nourishment, illness, and other factors; even varying among individuals in a single population
Population typically refers to the number of people in a single area, whether it be a city or town, region, country, continent, or the world. Governments typically quantify the size of the resident population within their jurisdiction using a ...
. ''Proteus anguinus'' is now considered a single species. The length of the head is the most obvious difference between the various populations – individuals from Stična, Slovenia, have shorter heads on average than those from Tržič
Tržič (; german: Neumarktl) is a town in northern Slovenia, close to the Austrian border. It is the seat of the Municipality of Tržič.
Geography
The town is located within the historic Upper Carniola region on the Tržič Bistrica River, ...
, Slovenia, and the Istria
Istria ( ; Croatian language, Croatian and Slovene language, Slovene: ; ist, Eîstria; Istro-Romanian language, Istro-Romanian, Italian language, Italian and Venetian language, Venetian: ; formerly in Latin and in Ancient Greek) is the larges ...
n peninsula, for example.
Black olm
The black olm (''Proteus anguinus parkelj'' Sket & Arntzen, 1994) is the only other recognized subspecies of the olm. It is endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to the underground waters near Črnomelj
Črnomelj (; in older sources also ''Černomelj'', german: Tschernembl''Leksikon občin kraljestev in dežel zastopanih v državnem zboru,'' vol. 6: ''Kranjsko''. 1906. Vienna: C. Kr. Dvorna in Državna Tiskarna, p. 4.) is a town in southeastern S ...
, Slovenia, an area smaller than . It was first found in 1986 by members of the Slovenian Karst Research Institute, who were exploring the water from Dobličica karst spring in the White Carniola
White Carniola ( sl, Bela krajina; german: Weißkrain or ''Weiße Mark'') is a traditional region in southeastern Slovenia on the border with Croatia. Due to its smallness, it is often considered a subunit of the broader Lower Carniola region, alth ...
region.[Sket B. ''et al.'' (ed.) (2003). (''The animals of Slovenia''). Ljubljana: Tehniška založba Slovenije. ]
It has several features separating it from the nominotypical subspecies
In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
(''Proteus a. anguinus''):
These features suggest that the black olm has probably colonized underground habitats more recently and still retains some nontroglomorphic characteristics.
Research history
The first written mention of the olm is in Johann Weikhard von Valvasor
Johann Weikhard Freiherr von Valvasor or Johann Weichard Freiherr von Valvasor ( sl, Janez Vajkard Valvasor, ) or simply Valvasor (baptised on 28 May 1641 – September or October 1693) was a natural historian and polymath from Carniola, pr ...
's ''The Glory of the Duchy of Carniola
''The Glory of the Duchy of Carniola'' (german: Die Ehre deß Hertzogthums Crain, sl, Slava vojvodine Kranjske) is an encyclopedia published in Nuremberg in 1689 by the polymath Johann Weikhard von Valvasor. It is the most important work on his ...
'' (1689) as a baby dragon
A dragon is a reptilian legendary creature that appears in the folklore of many cultures worldwide. Beliefs about dragons vary considerably through regions, but dragons in western cultures since the High Middle Ages have often been depicted as ...
. Heavy rains of Slovenia would wash the olms up from their subterranean habitat, giving rise to the folklore belief that great dragons lived beneath the Earth's crust, and the olms were the undeveloped offspring of these mythical beasts. In his book Valvasor compiled the local Slovenian folk stories and pieced together the rich mythology of the creature and documented observations of the olm as "Barely a span long, akin to a lizard, in short, a worm and vermin of which there are many hereabouts".
The first researcher to retrieve a live olm was a physician and researcher from Idrija
Idrija (, in older sources ''Zgornja Idrija''; german: (Ober)idria, it, Idria) is a town in western Slovenia. It is the seat of the Municipality of Idrija. It is located in the traditional region of Inner Carniola and is in the Gorizia Statistic ...
, Giovanni Antonio Scopoli
Giovanni Antonio Scopoli (sometimes Latinisation of names, Latinized as Johannes Antonius Scopolius) (3 June 1723 – 8 May 1788) was an Italian physician and natural history, naturalist. His biographer Otto Guglia named him the "first anational ...
, who sent dead specimens and drawings to colleagues and collectors. Josephus Nicolaus Laurenti
Josephus Nicolaus Laurenti (4 December 1735, Vienna – 17 February 1805, Vienna) was an Austrian naturalist and zoologist of Italian origin.
Laurenti is considered the auctor of the class Reptilia (reptiles) through his authorship of ' (1768) ...
, though, was the first to briefly describe the olm in 1768 and give it the scientific name ''Proteus anguinus''. It was not until the end of the century that Carl Franz Anton Ritter von Schreibers
Carl Franz Anton Ritter von Schreibers (15 August 1775 – 21 May 1852) was an Austrian naturalist who was a native of Pressburg, Hungary, Habsburg Empire (today Bratislava, Slovakia).
In 1847, an uncommon iron-nickel-phosphide ((Fe,Ni)3P) miner ...
from the Naturhistorisches Museum
The Natural History Museum Vienna (german: Naturhistorisches Museum Wien) is a large natural history museum located in Vienna, Austria. It is one of the most important natural history museums worldwide.
The NHM Vienna is one of the largest museum ...
of Vienna
en, Viennese
, iso_code = AT-9
, registration_plate = W
, postal_code_type = Postal code
, postal_code =
, timezone = CET
, utc_offset = +1
, timezone_DST ...
started to look into this animal's anatomy. The specimens were sent to him by Sigmund Zois
Sigmund Zois Freiherr von Edelstein, usually referred as Sigmund Zois ( sl, Žiga Zois, formerly Slovenized as ''Cojs'' or ''Cojz''; ) (23 November 1747 – 10 November 1819) was a Carniolan nobleman, natural scientist and patron of the arts. He ...
. Schreibers presented his findings in 1801 to The Royal Society
The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
in London
London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
, and later also in Paris
Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...
. Soon, the olm started to gain wide recognition and attract significant attention, resulting in thousands of animals being sent to researchers and collectors worldwide. A Dr Edwards was quoted in a book of 1839 as believing that "...the Proteus Anguinis is the first stage of an animal prevented from growing to perfection by inhabiting the subterraneous waters of Carniola."
In 1880 Marie von Chauvin began the first long-term study of olms in captivity. She learned that they detected prey's motion, panicked when a heavy object was dropped near their habitat, and developed color if exposed to weak light for a few hours a day, but could not cause them to change to a land-dwelling adult form, as she and others had done with axolotl
The axolotl (; from nci, āxōlōtl ), ''Ambystoma mexicanum'', is a paedomorphic salamander closely related to the tiger salamander. Axolotls are unusual among amphibians in that they reach adulthood without undergoing metamorphosis. Instea ...
.
The basis of functional morphological investigations in Slovenia was set up by Lili Istenič in the 1980s. More than twenty years later, the Research Group for functional morphological Studies of the Vertebrates in the Department of Biology (Biotechnical Faculty, University of Ljubljana
The University of Ljubljana ( sl, Univerza v Ljubljani, , la, Universitas Labacensis), often referred to as UL, is the oldest and largest university in Slovenia. It has approximately 39,000 enrolled students.
History Beginnings
Although certain ...
), is one of the leading groups studying the olm under the guidance of Boris Bulog. There are also several cave laboratories in Europe in which olms have been introduced and are being studied. These are Moulis, Ariège (France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...
), Kent's Cavern
Kents Cavern is a cave system in Torquay, Devon, England. It is notable for its archaeological and geological features. The cave system is open to the public and has been a geological Site of Special Scientific Interest since 1952 and a Schedu ...
(England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...
), Han-sur-Lesse
Han-sur-Lesse (; wa, Han-so-Lesse) is a village of Wallonia and a district of the municipality of Rochefort, located in the province of Namur, Belgium. Han-sur-Lesse was called Ham from 1139, Ham Han Sur Lesche, from 1266, Han Sur Lece from 1465 a ...
(Belgium
Belgium, ; french: Belgique ; german: Belgien officially the Kingdom of Belgium, is a country in Northwestern Europe. The country is bordered by the Netherlands to the north, Germany to the east, Luxembourg to the southeast, France to th ...
) and Aggtelek
Aggtelek (meaning "Old plot" in Hungarian) is a village in the county of Borsod-Abaúj-Zemplén, Hungary. It is known for the vast stalactite caverns of the nearby Baradla-Domica cave system, part of the UNESCO World Heritage Site of Aggtelek ...
(Hungary
Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia a ...
). They were also introduced into the Hermannshöhle (Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
) and Oliero (Italy
Italy ( it, Italia ), officially the Italian Republic, ) or the Republic of Italy, is a country in Southern Europe. It is located in the middle of the Mediterranean Sea, and its territory largely coincides with the homonymous geographical re ...
) caves, where they still live today. Additionally, there is evidence that a small number of olms were introduced to the United Kingdom in the 1940s, although it's highly likely that the animals perished shortly after being released.
The olm was used by Charles Darwin
Charles Robert Darwin ( ; 12 February 1809 – 19 April 1882) was an English naturalist, geologist, and biologist, widely known for his contributions to evolutionary biology. His proposition that all species of life have descended fr ...
in his seminal work ''On the Origin of Species
''On the Origin of Species'' (or, more completely, ''On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life''),The book's full original title was ''On the Origin of Species by Me ...
'' as an example for the reduction of structures through disuse:[Darwin C. (1859). ''On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life''. London: John Murray.]
An olm (Proteus) genome project is currently underway by the University of Ljubljana
The University of Ljubljana ( sl, Univerza v Ljubljani, , la, Universitas Labacensis), often referred to as UL, is the oldest and largest university in Slovenia. It has approximately 39,000 enrolled students.
History Beginnings
Although certain ...
and BGI. With an estimated genome size roughly 15-times the size of human genome, this will likely be the largest animal genome sequenced so far.
Conservation
The olm is extremely vulnerable to changes in its environment, due to its adaptation to the specific conditions in caves. Water resources in the karst are extremely sensitive to all kinds of pollution. The contamination of the karst underground waters is due to the large number of waste disposal sites leached by rainwater, as well as to the accidental overflow of various liquids. The reflection of such pollution in the karst underground waters depends on the type and quantity of pollutants, and on the rock structure through which the waters penetrate. Self-purification processes in the underground waters are not completely understood, but they are quite different from those in surface waters.
Among the most serious chemical pollutants
A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like oi ...
are chlorinated hydrocarbon pesticide
Pesticides are substances that are meant to control pests. This includes herbicide, insecticide, nematicide, molluscicide, piscicide, avicide, rodenticide, bactericide, insect repellent, animal repellent, microbicide, fungicide, and lampri ...
s, fertilizer
A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...
s, polychlorinated biphenyls (PCBs
Polychlorinated biphenyls (PCBs) are highly carcinogenic chemical compounds, formerly used in industrial and consumer products, whose production was banned in the United States by the Toxic Substances Control Act in 1979 and internationally by t ...
), which are or were used in a variety of industrial processes and in the manufacture of many kinds of materials; and metals such as mercury, lead, cadmium, and arsenic. All of these substances persist in the environment, being slowly, if at all, degraded by natural processes. In addition, all are toxic to life if they accumulate in any appreciable quantity.
The olm was included in annexes II and IV of the 1992 EU Habitats Directive
The Habitats Directive (more formally known as Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora) is a directive adopted by the European Community in 1992 as a response to the Berne Convention. The E ...
(92/43/EEC). The list of species in annex II, combined with the habitats listed in annex I, is used by individual countries to designate protected area
Protected areas or conservation areas are locations which receive protection because of their recognized natural, ecological or cultural values. There are several kinds of protected areas, which vary by level of protection depending on the ena ...
s known as 'Special Areas of Conservation'. These areas, combined with others created by the older Birds Directive
The Birds Directive (formally known as Council Directive 2009/147/EC on the conservation of wild birds) is the oldest piece of EU legislation on the environment and one of its cornerstones which was unanimously adopted in April 1979 as the Dire ...
were to form the Natura 2000
Natura 2000 is a network of nature protection areas in the territory of the European Union. It is made up of Special Areas of Conservation and Special Protection Areas designated under the Habitats Directive and the Birds Directive, respectively ...
network. Annex IV additionally lists "animal and plant species of community interest in need of strict protection", although this has little legal ramifications.[Habitats directive](_blank)
(1992) ''ec.europa.eu'' Postojna Cave
Postojna Cave ( sl, Postojnska jama; german: Adelsberger Grotte; it, Grotte di Postumia) is a long karst cave system near Postojna, southwestern Slovenia. It is the second-longest cave system in the country (following the Migovec System) as wel ...
and other caves inhabited by the olm were eventually included in the Slovenian part of the Natura 2000 network. Capturing or killing olm is allowed only under specific circumstances determined by the local authorities (i.e. scientific study).
The olm was first protected in Slovenia in 1922 along with all cave fauna, but the protection was not effective and a substantial black market came into existence. In 1982 it was placed on a list of rare and endangered species. This list also had the effect of prohibiting trade of the species. After joining the European Union
The European Union (EU) is a supranational political and economic union of member states that are located primarily in Europe. The union has a total area of and an estimated total population of about 447million. The EU has often been des ...
in 2004, Slovenia had to establish mechanisms for protection of the species included in the EU Habitats Directive. The olm is included in a ''Slovenian Red list'' of endangered species.[''Slovenian official gazette'' (2002)]
no. 82, Tuesday 24 September 2002
In Croatia, the olm is protected by the legislation designed to protect amphibians – collecting is possible only for research purposes by permission of the National Administration for Nature and Environment Protection. As of 2020 the Croatian population has been assessed as ' critically endangered' in Croatia. As of 1999, the environmental laws in Bosnia and Herzegovina
Bosnia and Herzegovina ( sh, / , ), abbreviated BiH () or B&H, sometimes called Bosnia–Herzegovina and often known informally as Bosnia, is a country at the crossroads of south and southeast Europe, located in the Balkans. Bosnia and H ...
and Montenegro
)
, image_map = Europe-Montenegro.svg
, map_caption =
, image_map2 =
, capital = Podgorica
, coordinates =
, largest_city = capital
, official_languages = M ...
had not yet been clarified for this species.
In the 1980s the IUCN
The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
claimed that some illegal collection of this species for the pet trade took place, but that the extent of this was unknown: this text has been copied into all subsequent assessments. Since the 1980s until the most recent assessment in 2008 the organisation has rated the conservation status for the IUCN Red List
The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
as ' vulnerable', this because of its natural distribution being fragmented over a number of cave systems as opposed to being continuous, and what they consider a decline in extent and quality of its habitat, which they assume means that the population has been decreasing for the last 40 years.
Zagreb Zoo
Zagreb Zoo ( hr, Zoološki vrt Grada Zagreba) is a zoo located within Maksimir Park in Zagreb, Croatia and is across the street from Zagreb's Maksimir Stadium. It is one of three zoo parks in the country.
Zagreb Zoo is a member of both the Eur ...
is a zoo
A zoo (short for zoological garden; also called an animal park or menagerie) is a facility in which animals are kept within enclosures for public exhibition and often bred for Conservation biology, conservation purposes.
The term ''zoological g ...
in Croatia that houses the olm.[ Olms were until recently formerly kept in numerous zoos in Germany, as well as in the UK, Belgium and Slovenia. At present they can only be experienced at Zagreb Zoo, ''Hermannshöhle'' in Germany and Vivarium Proteus (Proteus Vivarium) within ''Postojnska jama'' (Postojna Cave) in Slovenia. There are also captive breeding programs in France and Germany.
]
Cultural significance
The olm is a symbol of Slovenian natural heritage. The enthusiasm of scientists and the broader public about this inhabitant of Slovenian caves is still strong 300 years after its discovery. Postojna Cave
Postojna Cave ( sl, Postojnska jama; german: Adelsberger Grotte; it, Grotte di Postumia) is a long karst cave system near Postojna, southwestern Slovenia. It is the second-longest cave system in the country (following the Migovec System) as wel ...
is one of the birthplaces of biospeleology due to the olm and other rare cave inhabitants, such as the blind cave beetle. The image of the olm contributes significantly to the fame of Postojna Cave, which Slovenia successfully utilizes for the promotion of ecotourism
Ecotourism is a form of tourism involving responsible travel (using sustainable transport) to natural areas, conserving the environment, and improving the well-being of the local people. Its purpose may be to educate the traveler, to provide funds ...
in Postojna
Postojna (; german: Adelsberg, it, Postumia) is a town in the traditional region of Inner Carniola, from Trieste, in southwestern Slovenia. It is the seat of the Municipality of Postojna. and other parts of Slovenian karst. Tours of Postojna Cave also include a tour around the speleobiological station – the Proteus vivarium
A vivarium (Latin, literally for "place of life"; plural: ''vivaria'' or ''vivariums'') is an area, usually enclosed, for keeping and raising animals or plants for observation or research. Water-based vivaria may have open tops providing they a ...
, showing different aspects of the cave environment.[Destinacija Postojna](_blank)
. Retrieved 7 June 2007.
The olm was also depicted on one of the Slovenian tolar
The tolar was the currency of Slovenia from 8 October 1991 until the introduction of the euro on 1 January 2007. It was subdivided into 100 ''stotinov'' (cents). The ISO 4217 currency code for the Slovenian tolar was ''SIT''. From October 1991 un ...
coins. It was also the namesake of ''Proteus'', the oldest Slovenian popular science magazine, first published in 1933.
References
External links
EDGE of Existence Olm information
Proteus magazine
* ttps://web.archive.org/web/20070517141401/http://www.arkive.org/species/GES/amphibians/Proteus_anguinus/ The olm on ARKivenbsp;– pictures, films
The olm
on the pages of the Slovenian Natural history museum
The Global Amphibian Assessment – Proteus anguinus
{{Featured article
Amphibians of Europe
Amphibians described in 1768
Cave salamanders
Electroreceptive animals
Fauna of Bosnia and Herzegovina
Fauna of Croatia
Fauna of Slovenia
Oligotrophs
Postojna Cave
Proteidae
Taxa named by Josephus Nicolaus Laurenti