Body size and skeletal muscle myoglobin of cetaceans: adaptations for maximizing dive duration

Cetaceans exhibit an exceptionally wide range of body mass that influence b oth the capacities for oxygen storage and utilization; the balance of these factors is important for defining dive limits. Furthermore, myoglobin cont ent is a key oxygen store in the muscle as it is many times higher in marin e mammals than terrestrial mammals. Yet little consideration has been given to the effects of myoglobin content or body mass on cetacean dive capacity . To determine the importance of myoglobin content and body mass on cetacea n diving performance, we measured myoglobin content of the longissimus dors i for ten odontocete (toothed whales) and one mysticete (baleen whales) spe cies ranging in body mass from 70 to 80 000 kg. The results showed that myo globin content in cetaceans ranged from 1.81 to 5.78 g (100 g wet muscle)(- 1). Myoglobin content and body mass were both positively and significantly correlated to maximum dive duration in odontocetes; this differed from;he r elationship for mysticetes. Overall, the combined effects of body mass and myoglobin content accounts for 50% of the variation in cetacean diving perf ormance. While independent analysis of the odontocetes showed that body mas s and myoglobin content accounts for 83% of the variation in odontocete div e capacity. (C) 2000 Elsevier Science Inc. All rights reserved.