Certain fruit flies of the genus Drosophila make the world's longest sperm. One species that biologist Daniel Lachaise studies makes sperm that are two-thirds of an inch long--more than 300 times longer than human sperm, 600 times longer than hippopotamus sperm (which are the world's shortest), and 6 times longer than the fly itself. The fly is not ripped apart by its own stupendous sex cells, however, because the sperm are hair-thin and all balled up. Still, making such gametes is a considerable effort for a small insect. In humans, says Lachaise, an equivalent energy investment would mean that males would make sperm 40 feet long.
It sounds like a colossal waste, and in fact many species of Drosophila take the more conventional approach of making lots of tiny sperm. But according to Lachaise and his colleagues at the National Center for Scientific Research in Paris and the University of ...
