Allometric scaling of metabolic rate and cardiorespiratory variables in aquatic and terrestrial mammals.

While basal metabolic rate (BMR) scales proportionally with body mass (M ), it remains unclear whether the relationship differs between mammals from aquatic and terrestrial habitats. We hypothesized that differences in BMR allometry would be reflected in similar differences in scaling of O delivery pathways through the cardiorespiratory system. We performed a comparative analysis of BMR across 63 mammalian species (20 aquatic, 43 terrestrial) with a M range from 10 kg to 5318 kg.