Fig. 1. Graphs of cost of transport against body mass M_b for running animals. The upper line shows the net metabolic cost, and the lower one the mechanical cost (ignoring fluctuations of internal kinetic energy, and energy saving by elastic mechanisms). On the horizontal axis, 0.1 mg should read 0.1 g. From R. J. Full: Mechanics and energetics of terrestrial locomotion: bipeds to polypeds. In Energy Transformations in Cells and Organisms (ed. W. Wieser and E. Gnaiger), pp. 175-182. Stuttgart: Thieme. Reprinted by permission.