By Susan Milius
Tiny male spiders of a species common to the southeastern United States routinely remove one of their two oversize external sex organs. It’s an extreme act, but one that apparently enables them to run faster and longer, a potential advantage for winning mates, researchers say.
As is typical in spiders, a male of Tidarren sisyphoides develops two protrusions with hollow tips, or pedipalps, on the front of his body for delivering sperm, explains Duncan J. Irschick of Tulane University in New Orleans. The male spider grows to only about one-hundredth the size of a female, yet one pedipalp accounts for some 10 percent of his body mass.