Amphibians
Zigzag Salamander
Plethodon dorsalis · also called southern zigzag salamander
A zigzag salamander has no lungs at all, breathing entirely through its damp skin and the lining of its mouth, which is exactly why it never strays far from cool, moist forest litter and limestone crevices. It never passes through a tadpole stage either — eggs laid on land, guarded by the mother, hatch directly into fully formed miniature salamanders.
Overview
The zigzag salamander, Plethodon dorsalis, is a small, lungless woodland salamander of the central and eastern United States, named for the irregular, jagged stripe running down its back. It hunts tiny invertebrates in leaf litter and rock crevices, strongly tied to cool, limestone-rich habitat.
No lungs, no tadpoles
Breathing entirely through skin and mouth lining, it depends on staying consistently damp. Eggs laid in a hidden, moist spot on land — often guarded by the mother — skip any aquatic larval stage and hatch straight into miniature salamanders. If grabbed, it can shed a still-wriggling decoy tail to escape.
Status
Least Concern — reasonably common across suitable forest and rocky habitat, though locally sensitive to logging and drought that dry out the ground-level microhabitats it depends on.
Zigzag Salamander: common questions
How does a zigzag salamander breathe without lungs?
It absorbs oxygen directly through its thin, permanently moist skin and through the lining of its mouth, a process called cutaneous respiration that entirely replaces the need for lungs, which the whole lungless salamander family, Plethodontidae, has lost over the course of its evolution. This mode of breathing is highly efficient but depends completely on the skin staying damp, which is why zigzag salamanders are almost always found in cool, consistently humid microhabitats such as leaf litter, rotting logs, and rock crevices rather than in dry, exposed conditions.
Does the zigzag salamander have a tadpole-like stage?
No, the species skips a free-living aquatic larval stage entirely through a process called direct development, in which eggs laid in a moist, hidden location on land, rather than in a pond or stream, hatch straight into fully formed miniature salamanders. This frees the zigzag salamander from any dependence on standing or flowing water for reproduction, allowing it to complete its entire life cycle on land within suitably moist forest and rock habitat.
Why does the stripe pattern vary so much between individuals?
The zigzag salamander shows considerable natural variation in the exact colour, width, and jaggedness of its characteristic dorsal stripe, both between individuals within the same population and, in some cases, between different populations across its range. This kind of variable colour pattern is common among lungless salamanders generally and is thought to reflect a combination of genetic variation and, in some related species, localised evolutionary responses to slightly different predator communities or habitat conditions in different parts of the range.
What does a zigzag salamander do if a predator grabs it?
Its skin produces distasteful or mildly toxic secretions that can discourage many predators from continuing an attack, and if seized despite this, the salamander can voluntarily detach its tail, leaving behind a separate piece that continues to wriggle and distract the predator's attention while the salamander itself escapes to safety. Over time the lost tail portion is slowly regrown, though the replacement is typically shorter and sometimes differently coloured or textured than the original.