Figure 2.

Motility of sperm bundles and solitary spermatozoa in C. savignyi. (a) Average motility of sperm bundles (solid line) and solitary spermatozoa (dotted line) with increasing viscosity of medium (PVP addition, in per cent). Sperm bundles display significantly greater average velocity than solitary spermatozoa (Kruskal–Wallis χ² = 114.13, d.f. = 1, p < 0.001). Treatments with different lower case letters differed significantly (after Bonferroni correction, Kruskal–Wallis χ²). See table 1 for numeric values and sample sizes. (b) Mean sperm bundle velocity versus solitary sperm velocity for each male. Dotted line indicates a similar velocity for bundles and solitary spermatozoa. Sperm bundles display higher velocity for 27 males (above the line) out of 34.