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Olm

life science Maturity 7-9 Next article →

The olm, scientifically known as Proteus anguinus, is a unique aquatic salamander.

Protée aveugle
Protée aveugle

It is the only species in the genus Proteus. It is also the only chordate that lives exclusively in European caves. These animals live in the underground waters of the Dinaric Alps. This habitat consists of limestone bedrock known as karst. The waters flow through regions including Italy, Slovenia, Croatia, and Bosnia and Herzegovina. Because they are entirely aquatic, they eat, sleep, and breed underwater.

P anguinus-head
P anguinus-head

The olm is highly adapted to a life of permanent darkness. Its eyes are regressed and covered by a layer of skin. This means the olm is blind. However, it uses other senses to navigate its environment. The olm has a very thick nasal epithelium. This helps it sense organic compounds in the water through smell. It also uses taste buds located in the mucous epithelium of its mouth. These sensors allow the olm to detect the quality and quantity of prey.

P anguinus-head1
P anguinus-head1

Beyond smell, the olm uses advanced mechanical and electrical sensors. It possesses specialized sensory cells in the inner ear. These cells allow it to receive sound waves and ground vibrations. The olm is most sensitive to underwater sounds between 1,500 and 2,000 Hz. It can detect frequencies ranging from 10 Hz to over 12,000 Hz. Additionally, it has ampullary organs on its head for electroreception. These organs let the olm register weak electric fields. It even uses a lateral line to detect low-frequency water displacements. Some evidence suggests it may use Earth's magnetic field for orientation.

P anguinus1
P anguinus1

The physical appearance of the olm is quite distinct. It has a long, snakelike body that can reach up to 30 cm. Most specimens average between 23 and 25 cm in length. The skin is thin and lacks much pigment. This gives the olm a yellowish-white or pink color. You can see the red, oxygen-rich blood through the skin in its external gills. These gills appear as two branched tufts at the back of the head. One specific population is known as the black olm. These individuals are always pigmented and appear dark brown or black.

P anguinus-head
P anguinus-head

The olm exhibits a biological process called neoteny. This means it retains larval features throughout its entire adult life. For example, it keeps its external gills even as an adult. Its limbs are also reduced compared to other amphibians. The front legs have only three digits. The hind legs have only two digits. The body is cylindrical and segmented with furrows. The tail is short and flattened with a thin fin. This body shape helps the olm swim using serpentine movements.

Protée aveugle
Protée aveugle

The history of the olm includes early sightings by humans. A naturalist named Valvasor first mentioned the animal in 1689. He wrote about it in his book, Glory of the Duchy of Carniola. He noted that heavy rains sometimes washed olms out of underground waters. Local people believed these creatures were offspring of cave dragons. The name "olm" is a German loanword used in English during the late 19th century. In Slovenia, the animal is called močeril.

Survival in a cave requires extreme energy management. Food is often scarce in underground environments. The olm is a predator that eats snails, crustaceans, and insects. It swallows its prey whole without chewing. To survive long periods without meals, the olm stores nutrients in its liver. It stores these as deposits of lipids and glycogen. The olm can reduce its metabolic rate to save energy. Remarkably, controlled experiments show an olm can survive up to 10 years without food. This ability makes it a master of its specialized ecosystem.

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🖼️ Images & Media (7)
File:Protée aveugle.jpg
Protée aveugle.jpg
File:P anguinus-head1.jpg
P anguinus-head1.jpg
File:P anguinus1.jpg
P anguinus1.jpg
File:P anguinus-head.jpg
P anguinus-head.jpg
File:P anguinus parkelj-head.jpg
P anguinus parkelj-head.jpg
File:Researchventhole.jpg
Researchventhole.jpg
File:Proteus - Laurenti.jpg
Proteus - Laurenti.jpg
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