The new flatworms are all hermaphrodites, meaning they have both male and female parts. To reproduce they try to stab each other with their genitals. The first to penetrate inserts sperm and then goes on to spar with another flatworm, while the "loser" lays and broods the eggs.
A new sea creature discovered off the coast of Australia has an unusual trait: it fences with its penis. A new species of flatworm commonly known as oyster leeches engages in a strange sexual behavior described thusly:
at 10:13 PM