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Fig. 5. Plot of muscle mitochondrial volume density against body mass in athletic
(filled circles) and sedentary terrestrial mammals (small dots) and pinnipeds
(open symbols). The linear relationship (y=6.75-1.34[logx],
r2=0.70) was generated from the volume densities of the
vastus medialis, a primary locomotory muscle, from various terrestrial mammals
ranging in size from the dwarf mongoose to the steer
(Kanatous et al., 1999; and
terrestrial data from Hoppeler et al.,
1987). By contrast to the shorter-duration divers, the volume
density of mitochondria in the M. longissimus dorsi of Weddell seals was
similar to that predicted for a sedentary terrestrial mammal of comparable
size.