Salamanders belong to the order Caudata (meaning "tailed") of the family Amphibia; frogs, to the order Anura, or "tailless." Salamanders do not lose their tails like frogs do when they develop from tadpoles into adults. Nor do they develop long legs with upper and lower limbs.
山椒魚屬兩棲類中的有尾目（青蛙為無尾目），由蝌蚪變成體時，尾巴不退化，腳短、又不似青蛙有長短之別，只好用「爬」的。