ABOVE: This ultraviolet-enhanced image shows two Pseudopolydesmus serratus preserved in mating position.
© STEPHANIE WARE
Last summer, evolutionary biologist Xavier Zahnle invited fellow millipede researchers to a visual treat. A PhD student at the University of California, Davis, Zahnle had just produced digital images showing the rarely seen insides of the male sexual organ, or gonopod, of the millipede Pseudopolydesmus serratus. Zahnle’s collaborators eyed the images carefully, looking for answers to the decades-old question of how millipede males deliver sperm.
You really, really, really get a sense of how things are oriented, and what’s next to what.
Millipede sex is a shrouded affair that happens behind rows of legs. A female millipede’s sexual organs—a pair of vulvae—are located in the third body segment from the head. When she is ready to mate, she pushes her vulvae out from behind her legs. The male grabs her with his many legs, then clasps ...