Figure 4.

Movie 6 shows a sea urchin Hemicentrotus pulcherrimus sperm with its head held in the tip of a vibrating micropipette (top center) while the plane of pipette vibration is rotated. The first part (∼1 s) shows the planar bending of the sperm flagellum before vibration begins. The second part (∼1 min 20 s) shows the pipette tip vibrating; the bending plane of the flagellum rotates along with the plane of pipette vibration as the latter is rotated several complete revolutions. In the third part (∼15 s), the vibration is stopped abruptly; the flagellar bend plane then rotates spontaneously back to its original orientation. This rotation is fast at first and slows down for the last rotations (∼5.9-Mb QuickTime movie).