This small creature can live up to 100 years without needing to eat frequently. What is its secret?
The extraordinary survival ability of this strange creature belongs to the olm (scientific name: Proteus anguinus). It is a rare species of salamander that lives entirely underwater. Nicknamed the “human fish” due to its pale skin, the olm is the only vertebrate found in European caves.
According to experts, olms have both gills and lungs. They can grow up to 45 cm long and live up to 100 years. Their diet mainly consists of shrimp, snails, and other small aquatic creatures. They locate prey using a special membrane in their ears, which can detect even the slightest vibrations in the water.
As a fully aquatic amphibian, the olm eats, sleeps, and reproduces underwater without requiring sunlight. Its life in darkness has led to underdeveloped eyes, rendering it almost blind. However, it compensates with an acute sense of smell and taste, allowing it to navigate its environment effectively.
A Lazy Creature That Eats Once Every 10 Years
The olm does not need to eat frequently. When food becomes scarce, it slows down its metabolism, enabling it to survive for up to 10 years on a single meal.
Due to its deep cave habitat, surrounded by perpetual darkness, the olm has no need to move much to escape predators—because it has very few natural enemies.
In fact, the olm’s only true natural enemy is daylight. Exposure to sunlight can burn its sensitive skin, making it highly dependent on its dark, subterranean home.
Olms do not live in large groups. Despite their strong sense of smell, they are almost blind and exist in complete darkness underground and underwater.
Scientific Research and Ecological Importance
A study published in the journal Zoology in January 2020 highlighted that most research on olms has been conducted in laboratories, leading to a lack of ecological data from their natural habitats. Experts believe that studying this species can help monitor human impact on submerged cave ecosystems.
Furthermore, the olm’s infrequent reproductive activity and unique habitat make it highly vulnerable, serving as a sensitive biological indicator of environmental changes caused by human activities.
Dr. Gergely Balázs from Eötvös Loránd University in Budapest, Hungary, stated that despite being a remarkable species, olms remain understudied, particularly in their natural environment.
Since 2010, Dr. Balázs’ research team has undertaken a major project to study olms. In the Vruljak 1 cave system in eastern Herzegovina (Southern Europe), they have marked approximately 40 individual olms over the years and tracked their movements.
After more than a decade, researchers found that most olms moved less than 10 meters. Some individuals traveled slightly farther, but one particularly inactive olm stayed in the same spot for an astonishing 2,569 days—over seven years.
Dr. Balázs remarked, “They stay in one place and barely do anything.”
He further explained that olms only move when absolutely necessary, such as for reproduction, which occurs roughly once every 12.5 years. This finding underscores the extremely sedentary lifestyle of the species.
This study provides additional evidence supporting the evolution of animal species, as previously described by Charles Darwin.
