Olm
The olm, or proteus (Proteus anguinus), is the only
cavedwelling chordate species found in Europe. In contrast to most amphibians,
it is entirely aquatic, and it eats, sleeps, and breeds underwater.
Living in caves found in Dinaric
Alps, it is endemic to the waters
that flow underground through
extensive limestone of karst of
Central and Southeastern Europe,
specifically the southern Slovenia,
the Soča river basin near Trieste,
Italy, southwestern Croatia, and
Herzegovina.
This animal is most notable for its
adaptations to a life of complete
darkness in its underground
habitat. The olm's eyes are unde-
veloped, leaving it blind, while its
other senses, particularly those of
smell and hearing, are acutely
developed. It also lacks any
pigmentation in i its skin. It has three
toes on its forelimbs, but two toes
on its hind feet. It also exhibits neoteny, retaining larval
character istics like external gills into adulhood, like the American
amphibtians, the axolotl and the mudpuppy. The olm is the only species in the
Proteus genus, the only European species of the Proteidae family.
The olm's embryonic development takes 140 days, after which
it
takes another 14 years to reach
sexual maturity. The larvae gain
adult appearance after nearly four
months, with the duration of
development strongly correlating
with water temperature. Unconfirmed historical observations
of vivipary exist, but it has been shown that the females possess a gland that
produces the egg casing, similar to those of fish and egglaying amphibians. It
was long thought that female olm gave birth to live young at lower temperatures
and laid eggs at higher, but rigorous observations have not confirmed that. The
olm appears to be OViparous.
Olms from different cave systems differ substantially in
body measurements, color and some microscopic characters. Earlier
researchers used these differences to support the division
into five different 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.
The oim 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.
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 is one
of the birthplaces of speleobiology
due to the olm and other rare cave
inhabitants, such as the blind cave
beetle.
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