Bizarre Ghost-Like Salamander Has Stayed in the Same Spot for Over 7 Years

A ghost-like salamander in Eastern Europe has stayed in the same spot for seven years, scientists have announced.

The amphibian was discovered in an underwater cave in Bosnia and Herzegovina. It remained still for 2,569 days—or seven years and two weeks—straight.

Olms (Proteus anguinus) are the only species of their genus. They are essentially blind, retaining a limited ability to perceive light. Their other senses—touch, taste, hearing and magnetic—are more developed.

Olms colonized the underwater caves of Bosnia and Herzegovina, Croatia, Italy and Slovenia sometime between 8.8 million and 20 million years ago.

They are extraordinarily long-living creatures, with lifespans that can last more than a century. Their reproductive cycles take around 12.5 years to complete. They are also incredibly slow moving.

In a study published in the Journal of Zoology, researchers have now shown just how slow.

Divers tagged adult olms using a method that meant there was no need for them to be moved from their setting. The team tracked the movements of 19 individual olms over the course of the study. Individuals were tagged in stages, so some were monitored for 28 months, while others were tracked for eight years.

The most active individual of the bunch studied traveled 125 feet in 230 days. Most moved around 16 feet per year.

One particular individual showed extreme levels of stillness, not moving an inch during a seven-year timespan.

As the researchers explain, olms do not need to move. They exist in a world of darkness, food scarcity and minimal seasonal variation. They require little oxygen and appear to be resistant to starvation, able to go several years without food.

While the researchers stress they cannot offer any strong arguments as to why these animals move so little, they speculate it is because the long-living, slow-reproducing olms are "very energy cautious and limit their movements to the minimum."

Most studies examining the biology and behavior of olms are laboratory-based because of the difficulty reaching and assessing them in their natural habitat. This means the species is normally only observed in an artificial setting, rather in their natural habitat.

Even in these less-than-natural surroundings, olms have been shown to be spectacularly slow-moving, the team said.

The combined effect of being slow-moving and having long reproductive cycles means they are highly vulnerable to threats and changes in the environment. The study's authors describe the species as sensitive indicators for "habitat-changing human activities."

They conclude: "We hope that our study will stimulate researchers to study other P. anguinus populations, so we can see whether the extreme [low mobility] reported in the present paper is a general behaviour throughout the species' geographical distribution or is special to our study population."

Proteus anguinus
An olm perched on a cave. Locals used to believe these cave-dwelling amphibians were baby dragons. IvanaOK/iStock