Gas Exchange in Salamanders

Abstract

M EMBERS of the class Amphibia utilize every type of respiratory gas exchange known in the vertebrates-gills, lungs, skin, and buccopharyngeal mucosa-different species using them in various combinations. For example, the adults of most families of salamanders and frogs use skin, lung, and buccopharyngeal respiration, but the lungless salamanders of the family Plethodontidae use only buccopharyngeal and cutaneous gas exchange. Gills are common in the larval stages of most amphibians and cease to function at metamorphosis, but in some neotenic salamandrids and ambystomids gill respiration is retained in the adults. In aquatic, permanently larval Proteidae, such as Necturus maculosus, gills, skin, lungs, and buccopharyngeal mucosa may all be functional in respiration in sexually mature individuals (Noble, 1931). Thus, in their evolution the Amphibia have developed all the possible types of respiratory surfaces available to vertebrates. Since amphibians exhibit such a variety of mechanisms for respiratory exchange, a qualitative and quantitative knowledge of the relative roles of these respiratory surfaces in gas exchange in representatives of various families of am-