C. elegans are tiny worms that exist as hermaphrodites or rare
males. A male rubs against a hermaphrodite with the mating
apparatus on his tails and if he thinks she’s sexy enough, he’ll
try to mate with her. And what turns on a male worm? Answer: an
older lady. No one knows what the male is sensing on the
hermaphrodite to gauge her sex appeal. But now, researchers
Natalia Morsci, Leonard Haas, and Maureen Barr have discovered
that males respond to whether the hermaphrodite has active sperm
stored in her. Hermaphrodite worms technically don’t need to
mate. They can fertilize about 300 eggs all without ever
encountering a male. But once those 300 or so sperm are used up,
they can never make any more, even though they can make more
eggs. Hermaphrodites that mate will have about 1400 offspring
(compared to 300), which would seem to make mating the better
strategy. The catch? Hermaphrodites want to make sure they
fertilize as many of their eggs as possible with their own
sperm, so they can pass on more of their g