Respiratory Water Exchange in Two Species of Porpoise

Measurements of the respiratory water exchanges of Tursiops truncatus and Lagenorhynchus obli-quidens indicate that these species lose, respectively, only 30 and 77 percent as much water through evaporation as would terrestrial mammals of the same body weight. Control of temperature and pressure within the respiratory system and a lower ventilation rate account for this relatively small loss of water.