Fig. 3. Typical changes in tail midline shape during a tail beat illustrated by one individual. On the left are coordinates for the midline taken from a dorsal view and the curves that approximate their shape. The numbers at the end of the curves specify the corresponding time (t) in terms of the tail-beat cycle. The curvature profiles corresponding to these curves are shown on the right. (A,B) t=0.03 tail-beat cycles (shown in black), is within the first half of the tail beat (t<0.5) and tail motion is directed towards the right side of the body. At this moment, the section of the tail anterior to the inflection point (s<si) bends concave-right with a curvature equal to 
CR, and positions posterior to the inflection point (s>si) are bent concave-left with a curvature of CL. t=0.57 tail-beat cycles (shown in red) is within the second half of the tail beat (t>0.5), and the tail is moving towards the left side of the body. Tail curvature is equal to CL anterior to the inflection point (s<si) and to CR posterior to the inflection point (s>si). (C,D) Tail motion shown at 4ms intervals (roughly 0.03 tail-beat cycles) for the first half of a tail beat (t<0.5), when the tail is moving towards the right side of the body. Note that the magnitude of curvature in both directions (CL and CR) changes with time. (E,F) The motion during the left-directed, second half of the tail beat (t>0.5) shown at 4ms intervals. Again, curvature in both directions varies with time.
