Fig. 11. Relationship of frequency of stepping to overall running velocity in fiddler crabs. Data for Uca pugnax reanalyzed from Barnes (1975). Because of the limitations imposed by the 64 frames s^-1 filming rate, sequences of running with velocities above 35 cm s^-1 were not analyzed in the original report. The continuous line is the line of best fit for the data calculated by the method of least squares, while the broken line is a theoretical line which assumes that increases in velocity are produced entirely by increases in stepping frequency. The fact that the actual line is steeper than this indicates a small additional role for increases in step length (ca. 12% of total). Values (N=27) are means for sequences of locomotion varying in duration from 0.4 to 14 s.

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