Cave water in Dinaric karst carries little food, and what arrives comes in pulses after rain. The olm meets this with an extremely low metabolic rate and an ability to store nutrients in the liver, then reduce activity and even reabsorb body tissue when nothing is available. Laboratory animals have endured food deprivation for periods reported in years rather than months.
The same slow physiology appears elsewhere in its biology. Olms are exceptionally long-lived for a small amphibian, with estimates of maximum lifespan running past a century in the best-studied population, and they mature late and reproduce infrequently. A tracking study in a Bosnian cave found individuals that barely moved over years of observation.
The olm is often called blind, which is nearly right rather than exactly right. The eyes are undeveloped and covered by skin, but the animal remains light-sensitive through the skin and the residual eye, and larvae begin with better-formed eyes that regress during development.