After I observed the copulating rotifers, which swam around hectically, for about 60 minutes, the male separated from the female, calmed down significantly and was therefore much easier to photograph (B). The male, which was about the same size as the female, had a corona, two eyespots and a mastax, just like the female, but neither stomach nor intestine. Instead, the body was filled with a testicle, two globular prostate glands and a bladder (C; b: bladder, mx: mastax, pr: prostate glands, t: testicle).
Since I could not discern a penis, I presume that the foot of the male, which was inserted into the body of the female (D), served as penis.
All photographs were taken with a Canon Powershot G5 camera through a Plan-Neofluar 40x/0,75 objective attached to a Zeiss Axioskop, using brightfield illumination. The length of rotifers was about 75 µm (without foot).
Bernd
