Comparative Respiratory Physiology in Cetaceans

In the current study, we used breath-by-breath respirometry to evaluate respiratory physiology under voluntary control in a male beluga calf [Delphinapterus leucas, body mass range (M(b)): 151–175 kg], an adult female (estimated M(b) = 500–550 kg) and a juvenile male (M(b) = 279 kg) false killer whale (Pseudorca crassidens) housed in managed care. Our results suggest that the measured breathing frequency (f(R)) is lower, while tidal volume (V(T)) is significantly greater as compared with allometric predictions from terrestrial mammals. Including previously published data from adult bottlenose dolphin (Tursiops truncatus) beluga, harbor porpoise (Phocoena phocoena), killer whale (Orcinus orca), pilot whale (Globicephala scammoni), and gray whale (Eschrichtius robustus) show that the allometric mass-exponents for V(T) and f(R) are similar to that for terrestrial mammals (V(T): 1.00, f(R): −0.20). In addition, our results suggest an allometric relationship for respiratory flow ([Formula: see text]), with a mass-exponent between 0.63 and 0.70, and where the expiratory [Formula: see text] was an average 30% higher as compared with inspiratory [Formula: see text]. These data provide enhanced understanding of the respiratory physiology of cetaceans and are useful to provide proxies of lung function to better understand lung health or physiological limitations.