 When present in adult salamanders , lungs vary greatly among different species in size and structure . In aquatic , cold @-@ water species like the southern torrent salamander ( <unk> variegatus ) , the lungs are very small with smooth walls , while species living in warm water with little dissolved oxygen , such as the lesser siren ( Siren intermedia ) , have large lungs with convoluted surfaces . In the terrestrial lungless salamanders ( family Plethodontidae ) , no lungs or gills are present , and gas exchange mostly takes place through the skin , supplemented by the tissues lining the mouth . To facilitate this , these salamanders have a dense network of blood vessels just under the skin and in the mouth . 
