Fig. 2.

The motion of Ray sperms. The swimming motion of the Ray sperm in semen diluent (normal solution) is observed under the bright-field microscope shown in A and B. According to the images in A, i and ii and the rotational amplitude changes in A, iii, the rotating periods of head and tail were ∼20 ms and 120 ms, respectively. The average rotational speeds of the head and tail were 273.7 rad/s and 38.5 rad/s, respectively, from 33 samples shown in A, iv. Based on the recorded trajectory in B, their linearity and straightness were 81.6% and 95.1% (n = 29), respectively, which were obviously higher than those of the other six species. Bar = mean; error bar = SD.