Need for speed.(Samplings)(Brief Article)

Here's a consummately unequal partnership for you: male cobweb spiders (genus Tidarren) weigh in at only about 1 percent the weight of the females. Not surprisingly, that creates a few problems.

The male has two copulatory organs known as pedipalps, and either one can make him a dad. To do the job properly, each pedipalp has to be enormous, relative to the rest of his body. Sure enough, the two make up about 20 percent of his body weight--more, apparently, than he's willing to carry around. So, just before molting into his adult form, the male Tidarren half-emasculates himself. He spins a silk structure, ties it around one--just one--of his pedipalps, and then twists off the unwanted organ.

Working in the ...