The world's most successful salamanders breathe entirely through their own moist skin

Nature · Published 3 October 2026 Swipe more like this →

In short: Lungless salamanders, or Plethodontidae, are a biological paradox. Despite lacking lungs, they are the largest and most diverse family of salamanders on Earth. By mastering cutaneous respiration, these amphibians have unlocked a vast range of terrestrial habitats, from forest floors to high-altitude cloud forests, often becoming the dominant vertebrate biomass.

The family Plethodontidae comprises over 370 species that rely on gas exchange through their skin and mouth linings. To maintain this essential respiration, their surfaces must remain perpetually moist. This physiological constraint is supported by nasolabial grooves—channels extending from the nostrils to the upper lip—which use capillary action to transport chemical cues for food, alarm, and courtship to the vomeronasal organ. While they develop rudimentary lung structures as embryos, these regress through apoptosis within three weeks, leaving adults to rely on their skin for upwards of 83% to 93% of their oxygen intake.

This reliance on cutaneous respiration has not hindered their success; rather, it has facilitated a remarkable radiation into diverse environments. While some species remain aquatic or semi-aquatic, many have bypassed the need for water entirely through direct development, where embryos hatch as miniature adults rather than free-swimming larvae. This evolutionary shift allowed them to colonize terrestrial niches, from arboreal life in tropical epiphytes to rock crevices in arid regions. In some North American forests, their density is staggering; a single district in the Mark Twain National Forest is estimated to host 1.88 billion southern redback salamanders.

Their social lives are equally specialized, featuring complex courtship rituals unique among salamanders. Males often use mental glands under their chins to deliver pheromones to females, sometimes scratching them with enlarged teeth to ensure the chemicals penetrate. This behavior, combined with their ability to exploit tiny prey like springtails—which are often ignored by larger vertebrates—has allowed Plethodontidae to thrive with minimal competition. By reducing their metabolic rates, they can even survive prolonged hypoxia, proving that their lungless design is a sophisticated adaptation rather than a limitation.

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