Fig. 2. Head and flagellar measurements of Types 1 and 2 spermatozoa. (A) Principal components analysis (using sperm head length, width and length:width ratio) showed that the spermatozoa fell distinctly into the two groups (Types 1 and 2) with one outlier, and both sperm head length and width were significantly different (post-hoc ANOVA analyses: length, F_1/42=135.4, P<0.001; width, F_1/42=434.2, P<0.001, N=44). (B) Sperm heads of Type 1 spermatozoa measured 3.7 µm (median) in length (solid line), whereas sperm heads of Type 2 spermatozoa were significantly longer (dotted line), measuring 13.4 µm (median) in length. (C) Flagella of Type 1 spermatozoa (circles) varied in length between 6.3 and 69.3 µm (49.3 µm median), whereas flagellar lengths of Type 2 spermatozoa (triangles) ranged from 13.5 to 80.4 µm (25.1 µm median). The horizontal line in each group signifies the median value; ^*P=0.045 (N=44) indicates a significant difference by a Mann–Whitney test (two-tailed).