Ugly Fish Have Stronger Sperm

Pretty, colorful guppy guys may get all the ladies, but ugly guppies have “better sperm,” researchers concluded in a recent study. The group watched tropical guppies, and concluded that the colorful men had to “invest” in their beauty at the expense of slowing down their sperm. That's significant, because scientists believe guppy females mate with multiple males, and are ultimately impregnated by the fastest-swimming sperm.

Now, given their druthers, these ladies would only sleep with their most attractive suitors, but guppies engage in two kinds of reproductive behavior: traditional courtship, and “sneak mating,” or, as we humans might call it, “rape.” The males who mostly did the latter were less ornamented, but their sperm swam faster, the researchers tell the BBC, which might offset the colorful fishes' reproductive advantage.
(More guppies stories.)