Figure 1

Experimental setup and image analysis of sperm behaviour.
(a) Schematic of experimental setup (not drawn to scale). Arrows inside the petri dish indicate fluid flow direction. (b) Head angle, θ is defined as the angle between the major axis (red dashed line) of head ellipse (blue dashed ellipse) and flow direction. (c) Flagellar beating is described by the beating amplitude, A and asymmetry level, .
shown in the figure is the angle between the i-th point on the flagellum and the horizontal image axis.