Abstract
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 (Mb): 151–175 kg], an adult female (estimated Mb = 500–550 kg) and a juvenile male (Mb = 279 kg) false killer whale (Pseudorca crassidens) housed in managed care. Our results suggest that the measured breathing frequency (fR) is lower, while tidal volume (VT) 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 VT and fR are similar to that for terrestrial mammals (VT: 1.00, fR: −0.20). In addition, our results suggest an allometric relationship for respiratory flow (), with a mass-exponent between 0.63 and 0.70, and where the expiratory was an average 30% higher as compared with inspiratory . 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.
Highlights
Comparing respiratory traits between terrestrial and marine mammals shows some striking differences in that when normalized by body mass, breathing frequency (f R) is generally lower and tidal volume (VT) greater in marine mammals (Kooyman, 1973; Piscitelli et al, 2013; Fahlman et al, 2017)
In the current study we provide new respiratory measurements from spontaneous breaths that were within the range of those that provide accurate flow estimates (Finucane et al, 1972; Fahlman et al, 2019b), on a male beluga calf, a male juvenile and an adult female false killer whale
Our results suggest that the predicted f R is lower, while VT is significantly greater as compared with terrestrial mammals (Figures 1A,B)
Summary
Comparing respiratory traits between terrestrial and marine mammals shows some striking differences in that when normalized by body mass, breathing frequency (f R) is generally lower and tidal volume (VT) greater in marine mammals (Kooyman, 1973; Piscitelli et al, 2013; Fahlman et al, 2017). Respiratory flow (V ) is generally greater in marine mammals as compared with terrestrial species, especially in cetaceans, that have been shown to be able to generate expiratory flows (Vexp) that are at least one order of magnitude greater than in humans (Olsen et al, 1969a; Kooyman et al, 1971, 1975; Kooyman and Cornell, 1981; Piscitelli et al, 2013; Fahlman et al, 2015, 2017, 2019b). There appears to be great variability in the mechanical properties of the respiratory system, but in general marine mammals appear to have more compliant lung parenchyma as compared with terrestrial species, and a rib cage that allows the alveoli to compress and collapse without apparent trauma (Olsen et al, 1969b; Leith, 1976, 1989; Fahlman et al, 2011, 2017, 2018b; Denk et al, 2020). Data from different species are useful to help determine allometric differences within and between marine species, and in comparisons with terrestrial mammals
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
