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.
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