Respiratory surface area as a factor controlling the standard rate of O2 consumption of aquatic salamanders.

The standard rate of O2 consumption of various aquatic lunged salamanders is compared for animals breathing water only and for animals breathing both air and water. When submerged and prevented from surfacing in air-equilibrated water, most species studied were capable of survival for periods of at least two weeks. The animals that were allowed to respire bimodally exhibited an increased rate of O2 consumption relative to their submerged counterparts who were denied the use of pulmonary respiration. The standard rate of oxygen consumption is submerged and air-and-water-breathing Siren lacertina was determined over a large range of body size. The rate of the bimodally breathing animals was higher than that of the submerged animals, and the difference increased with increasing body size. These data suggest that it is the oxygen transport capacity of these animals that at least partially regulates the standard rate of O2 consumption rather than all such control being exerted at the cellular level.