Fig. 1. _CO2 (ml h^-1) for female (A) and male (B) tarantulas as a function of treadmill speed. Individual data points are shown for each animal, and the corresponding body mass is indicated. Least-squares linear regression lines are shown for aerobic (solid lines) and anaerobic (broken lines) speeds. The highest anaerobic speed of 126.3 m h^-1 achieved by the 14 g female is not shown (see Table 1). Individual results are based on single measurements at each speed.