* in earthworms Earthworms are hermaphroditic, yet they still
have to find mates. Although each worm produces both sperm and
ova, a worm cannot self-fertilize. Two worms must find each
other (not an easy task), exchange sperm, then later use the
partner’s sperm to fertilize its own eggs. Today my daughters
noticed two earthworms in a crack of our driveway, in flagrante
delicto. I grabbed my cameras, and caught a few good images. My
daughters were fascinated by what they saw, and a bit troubled
that their father was taking pictures of animals engaged in sex.
Here’s what was going on. The worm secretes sperm from pores on
Segment 15, and can store sperm from another worm in receptacles
on Segments 9 & 10. Its own ova are stored in oviducts that open
on Segment 13. Once they meet, the two worms line up in opposite
directions with their ventral surfaces touching; Segments 9 and
10 of each worm are aligned with the clitellum of its partner.
Setae (little hair-like structures that serve as anchors during
locomotion