An Olm Sat in One Spot for 2,569 Days

Gergely Balázs and his team at Eötvös Loránd University spent eight years pulling olms out of underwater cave passages in eastern Herzegovina, marking them, and putting them back. They were trying to answer a basic question nobody had ever bothered to settle: how much does a cave salamander actually get around.

The answer, published in the Journal of Zoology in 2020, was almost nothing. Across 19 tracked individuals, the average olm moved a little over five metres in a year. The most active one managed about 38 metres in 230 days. One animal, when the team came back to recapture it, was sitting exactly where they had left it. The interval between sightings was 2,569 days — just over seven years. "They are hanging around, doing almost nothing," Balázs told reporters at the time.

This is not torpor. The olm's metabolism, when measured, is unremarkable for an amphibian its size. It just doesn't have anywhere to go. Its caves have no light, no seasons, almost no current, and very little food — the occasional crustacean drifting past in the dark. So Proteus anguinus hangs in the water column, breathes through external red gills it never sheds, and waits.

The rest of its life runs at the same speed. Females lay eggs roughly every 12.5 years. Individuals reach sexual maturity around 16. A 2010 paper in Biology Letters projected a maximum lifespan over 100 years, with no measurable decline in old animals. A creature that can live a century in a place where nothing ever happens has no reason to be in a hurry.