Amphibians
Salamander
Caudata · also called urodele
A salamander looks like a lizard that has been left out in the rain — the same low body and long tail, but skin that is soft, moist, and scaleless. It is an amphibian, not a reptile, and as a group salamanders can do something no mammal can: regrow a whole leg, or a tail, or part of a heart, and leave no scar.
Overview
Salamanders are the amphibian order Caudata, around 800 species, the tailed counterpart to the frogs. A salamander keeps its long tail for life, has moist glandular skin, and hunts invertebrates by a slow stalk and a quick snap. They live in cool, damp habitats of the Northern Hemisphere, and the southern Appalachians hold more species than anywhere else on Earth.
Lungless, and forever young
About two thirds of all salamanders belong to the lungless family, breathing entirely through skin and mouth. And many species are paedomorphic — they keep their larval gills and stay aquatic for life, like the axolotl, the mudpuppy, the olm, and the sirens.
Regeneration, poison, and myth
Salamanders are the best limb-regenerators among vertebrates, rebuilding limbs, tail, jaw, and parts of the eye, heart, and spinal cord. Many have toxic skin, and the fire salamander’s habit of crawling out of burning logs gave rise to the myth that it lives in fire.
Status
Salamanders as an order are Not Evaluated, but a large share of species are threatened, especially in Mexico and Central America, and a salamander-specific fungal disease, Bsal, is spreading in Europe and threatens North America.
Salamander: common questions
Is a salamander a lizard or an amphibian?
An amphibian, not a lizard, despite the similar shape. Lizards are reptiles, with dry scaly skin, clawed toes, and eggs that can be laid on land in a protective shell. A salamander has soft, moist, scaleless skin through which it can absorb water and oxygen, unclawed toes, and eggs that lack a hard shell and are usually laid in water or in very damp ground. Salamanders also cannot tolerate dry conditions and are tied to moisture, while many lizards thrive in deserts. If you find a small tailed animal with slimy skin under a log or in a stream, it is a salamander; if it has dry scaly skin and scampers off in the sun, it is a lizard.
What is the difference between a salamander and a newt?
All newts are salamanders, but not all salamanders are newts. Salamander is the name for the whole order. Newt is used for certain members of one family, the Salamandridae, that make a strong seasonal move into water to breed and then back onto land, and that tend to have rougher, less slimy skin than the fully terrestrial or fully aquatic salamanders. So a small tailed amphibian found breeding in a garden pond in spring, with a crest on the male, is a newt, while a lungless woodland salamander of an Appalachian stream, or a giant permanently aquatic species like the hellbender, is a salamander that is not a newt.
How do salamanders regrow lost body parts?
When a salamander loses a limb, the cells at the wound do not simply seal it over with scar tissue as a mammal would. Instead, a layer of skin cells covers the stump and signals nearby muscle, bone, and connective-tissue cells to switch off their specialised identity and revert to a flexible, stem-cell-like state, forming a growth zone called a blastema. That blastema then re-runs much of the original developmental programme, rebuilding the limb in the correct order and to the correct size, with new bones, muscles, blood vessels, and nerves, and finally the cells re-specialise. The process takes weeks to months and can be repeated many times. Understanding why salamanders can do this and humans cannot is a major goal of regeneration research.
Where does the fire salamander get its name?
From an old and mistaken belief that it could live in, or was born from, fire. Fire salamanders shelter in damp, rotten logs, and when such a log was brought indoors and put on a hearth, the heat would drive the salamander out, so people saw the animal emerging from the flames and concluded it had a special relationship with fire. Its bright black-and-yellow warning pattern, its cool, moist skin, and the fact that its skin secretions could briefly damp a small flame all added to the myth, which made the salamander a symbol of fire in alchemy and heraldry and gave the word salamander a second meaning as a fire spirit.