 The lungs in amphibians are primitive compared to those of amniotes , possessing few internal septa and large alveoli , and consequently having a comparatively slow diffusion rate for oxygen entering the blood . Ventilation is accomplished by buccal pumping . Most amphibians , however , are able to exchange gases with the water or air via their skin . To enable sufficient cutaneous respiration , the surface of their highly vascularised skin must remain moist to allow the oxygen to diffuse at a sufficiently high rate . Because oxygen concentration in the water increases at both low temperatures and high flow rates , aquatic amphibians in these situations can rely primarily on cutaneous respiration , as in the Titicaca water frog and the hellbender salamander . In air , where oxygen is more concentrated , some small species can rely solely on cutaneous gas exchange , most famously the plethodontid salamanders , which have neither lungs nor gills . Many aquatic salamanders and all tadpoles have gills in their larval stage , with some ( such as the axolotl ) retaining gills as aquatic adults . 
