Spined micrathena

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Micrathena gracilis: not, perhaps, the specific name that most of us who have tried to walk through an August woods sticky with her webs would have chosen. But is she not slender and graceful, this spider, apart from the spiked club of her abdomen?

The ventral side of her abdomen appears to bear the spiral template for the web, whose silk emerges from its central point. Every morning at dawn she spins her web anew, spanning some path or opening in the forest where the light pools. If a human or other animal should blunder into her web, she’ll have a new one completed in a couple of hours. If it lasts until sunset, she devours the silk, leaving only the three foundation threads. The forest of the night throbs with the call-and-response of katydids — a noise like the surf, or a bank of industrial looms — while hundreds of spiders quietly erase their work.

She too can stridulate, though I’ve never heard it: a low-pitched buzz or hiss, they say, designed to frighten off predators.

The male is a fraction of her size, and has only two, flattish spines where she has ten. His spinning is limited to a single, non-sticky strand that he lays across her web: a path bisecting the net that spans the path. He hides under a nearby leaf, waiting for the right moment to place himself at her service but not at her disposal.

They each have two copulatory organs, and each pair must make contact, necessitating some complicated gymnastics. To ensure success of this risky business, he dances vigorously at the end of his thread, making the entire web vibrate as he bobs and waggles his skinny rear end. I would have to suppose the female finds this spectacle deeply entrancing. During copulation, if all goes well, the male flips over onto the female’s abdomen, and she can return to hunting flies with her new appendage sprawled on his back among the graceful peaks.
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See here (PDF) for a complete description of the courtship and mating practices of M. gracilis.