Telmatobius culeus lives permanently underwater in Lake Titicaca, where the surface sits at roughly 3,812 metres and the partial pressure of oxygen is low. Its lungs are reduced, and it relies chiefly on cutaneous respiration. The characteristic loose folds of skin along the flanks and limbs raise the surface area available for gas exchange, and the skin is unusually thin and richly supplied with capillaries.
When oxygen runs short, the frog performs a bobbing motion, pushing water past the folds to renew the boundary layer, in effect ventilating its skin. Red blood cell counts are high and the cells are small, both consistent with life in a low-oxygen environment.
The population has fallen sharply. The frog is harvested for a blended drink sold as an aphrodisiac and tonic, and mass die-offs have followed pollution events in the lake's rivers, including one in 2016 in which many thousands of dead frogs were recovered from the Coata River. Introduced rainbow trout prey on tadpoles. The species is listed as Endangered.