Olm

olm

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Olms are somewhat large salamanders living in southern Europe. These weird looking amphibians are completely blind. Their skin is creamy white, but they sometimes look pink due to the blood vessels they have close to their skin. The picture below shows a close up of an olm’s head. You can see here the red gills it uses to breathe under water.

olm head

This next picture shows a special subspecies of olm that has darker skin.

ah-dive- 002

One thing that cannot be seen easily in any of these pictures is the translucency of the olm’s skin. Sometimes you can actually see the outline of its internal organs! Another weird thing about this animal’s skin is that it feels fleshy, which is unusual for an amphibian. Because of this, the olm is sometimes called the human fish, even though it is neither fish nor human. They are also sometimes called white salamanders or cave salamanders.

Size

Olms are the largest vertebrate troglobytes. Troglobytes are animals that live almost completely in caves. Bats are not considered troglobytes because they only spend the day time in caves and not the night time. These salamanders range in length from eight to twelve inches (20-30 cm), and they average closer to about 9 1/2 inches (24 cm). There are some places that say these amphibians can get up to sixteen inches (41 cm) long. Olms can weigh up to five ounces (142 g), which is about the weight of a deck of cards.

Diet

Cave salamanders normally feast on invertebrates. They will consume many different types of insects as well as worms and snails. Not all of their prey is invertebrates as they will also sometimes eat eggs and small fish. Other than it being animal matter, olms don’t really care what their food is, as long as they can fit their mouth around it. In captivity these animals are usually fed small fish, worms, or even pieces of raw meat. Because they are blind, these salamanders use a combination of touch, smell, and chemical detection to find their prey. If food is scarce or hard to catch, they do not need to worry. These animals can survive up to ten years without eating!

Habitat and range

Olms live in five different countries in southern Europe. These are Bosnia and Herzegovina (this is one country), Croatia, France, Italy, and Slovenia. Their range may extend south to Montenegro and Serbia, but this has not been proven. I said earlier that these amphibians are blind, And even if they were able to see, it would not do them much good. This is because they live in caves where there is little or no light. Another thing that is hard to tell from the pictures is that these creatures are almost entirely aquatic. Occasionally, usually only after hard rains, olms can be found in water above the surface. They are usually found deep below the surface, up to about 1,000 feet (300 m) underground. Because this habitat is hard to reach, there is not as much known about these animals as you might think.

Status and threats

The olm is classified as Vulnerable on the IUCN Red List. Caves are mysterious places. Because of this, people like to explore them. Tourists exploring the caves these salamanders live in can disturb them and maybe even pollute the water they live in. Their water is also polluted by runoff from industry on the surface. Chemicals used in manufacturing or agriculture sometimes seep down through the soil and make the water not pure. Their main natural predators are large fish and other amphibians. Rodents or birds may occasionally prey on them, but this is very rare due to the depth at which they live. Olms are sometimes sold into the pet industry, but there are currently legal measures in place to protect them from this.

Reproduction

Most male olms establish a territory during the breeding season. They only mate about once every decade. The territories are furiously protected from other males that may want to take over them. After mating, the cave salamander’s eggs develop in one of two ways. Some females will lay their eggs under some rocks where they then protect them until they hatch. Even with the protection, most of the eggs will fall to disease or predators. Some females will retain the eggs in their body and give birth to just about two well-developed larvae. The rest of the eggs are broken down to provide nutrients to the female and the young that do survive. Unlike with most amphibians, olms do not have a clear metamorphosis into adulthood. Although they do grow lungs as they get older, they will keep their external gills. The young cave salamanders are ready to mate for the first time between age seven and fourteen. They are very long lived and are estimated to be able to live up to 100 years!

Don’t forget to scroll down and comment your guess about what the next animal is!

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Sources:

Photo credits;

  • Olm – Nacionalni park Una
  • Olm head – Arne Hodalič
  • Black olm – Arne Hodalič
  • Mystery animal – Francesco Veronesi
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