Comparative Respiratory Physiology in Cetaceans

Abstract

In the current study, we used breath-by-breath respirometry to evaluate respiratory physiology under voluntary control in a male beluga calf [<i>Delphinapterus leucas</i>, body mass range (<i>M</i> _b): 151-175 kg], an adult female (estimated <i>M</i> _b = 500-550 kg) and a juvenile male (<i>M</i> _b = 279 kg) false killer whale (<i>Pseudorca crassidens</i>) housed in managed care. Our results suggest that the measured breathing frequency (<i>f</i> _R) is lower, while tidal volume (<i>V</i> _T) is significantly greater as compared with allometric predictions from terrestrial mammals. Including previously published data from adult bottlenose dolphin (<i>Tursiops truncatus</i>) beluga, harbor porpoise (<i>Phocoena phocoena</i>), killer whale (<i>Orcinus orca</i>), pilot whale (<i>Globicephala scammoni</i>), and gray whale (<i>Eschrichtius robustus</i>) show that the allometric mass-exponents for <i>V</i> _T and <i>f</i> _R are similar to that for terrestrial mammals (<i>V</i> _T: 1.00, <i>f</i> _R: -0.20). In addition, our results suggest an allometric relationship for respiratory flow ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mi>V</mml:mi> <mml:mo>.</mml:mo></mml:mover> </mml:math> ), with a mass-exponent between 0.63 and 0.70, and where the expiratory <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mi>V</mml:mi> <mml:mo>.</mml:mo></mml:mover> </mml:math> was an average 30% higher as compared with inspiratory <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover><mml:mi>V</mml:mi> <mml:mo>.</mml:mo></mml:mover> </mml:math> . 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.