Clever Female Spiders Use ‘Mating Plugs’ to Thwart Unwanted Sex

New research has disabused Spider scientists (technical term, I assure you) at the Smithsonian of a long-standing misconception that males of the “highly sexually dimorphic and polygamous” wink, wink, nudge, nudge giant wood spider persuasion would sever their own genitals during copulation with a female spider to create a “plug” so that no rivals could subsequently mate with her. That, as it turns out, isn’t where such plugs come from — female spiders produce the plugs to keep unwanted males away from their nether regions.

Giant wood spiders — Nephila pilipes for all you people who didn’t conflate Latin class with afternoon nap — are very sexually active. A lot of small male spiders compete with each other for the chance to mate with only a few really big female spiders, so biologists had initially figured that the plugs were some sort of adaptation the males had developed in order to gain a paternity advantage. During a new series of staged laboratory mating trials, however, researchers realized that no plugs were formed during mating. Instead, female spiders exposed to a lot a males eventually developed “amorphous plugs” while they were laying eggs, thus giving them the ability to avoid sexual conflict by preventing unwanted male spiders from mating with them.

Biologists Discover Female Spiders Produce Mating Plugs to Prevent Unwanted Sex from Males [ScienceDaily]