Fig. 3. (A) Tail-beat frequency (f) increases linearly with length-specific swimming speed (U₁). The equation for the line is f=1.5 U₁+2.4 (r²=0.98, P<0.0001). The regression is fitted to the mean tail-beat frequency values. (B) Stride length (distance moved for each tail beat) increases as swimming speed increases. Stride values are reported as a proportion of the total body length (L) as well as in absolute distance (cm). Values at each speed represent the mean of four tail beats (± S.E.M.) for each of the four individuals.