For male peacock spiders, the best dancers get the girl
Dance, little spider, dance. If you’re good enough, you just might win yourself a mate.
Male peacock spiders of the genus Maratus would be notable enough for their brightly colored abdominal flaps. But many of the spiders, native to Australia, have an even more special way of gaining attention: They wave their flaps and lift their elongated third legs in a little dance and vibrate to lure a female.
Is the female really paying attention to either the dancing or vibrations, though? To find out, Madeline Girard of the University of California, Berkeley and colleagues began with juvenile M. volans spiders collected from around Sydney, Australia. They constructed a courtship arena, stretching nylon pantyhose across a circular frame — the nylon would vibrate when the male did. They then set up 64 mating trials with a male and a virgin female, and 22 trials with a male and a previously mated female.
The females that had previous mating experience had no interest in mating again. The wiggled their abdomens to signal “no,” or outright attacked the guy to fend him off. The guys had far more luck with the virgin females, with 25 percent of those encounters ending with success. And males that put more effort into their visual display, spending more time both dancing and vibrating and kept in close proximity to — and in visual contact with — the female, tended to be the ones that got the girl.
Males that didn’t perform well enough weren’t just ignored, however. “Females demonstrated aggressive behaviors when unreceptive,” the researchers write, “particularly when males made less vibratory effort and performed leg waving at lower rates.” Those that didn’t dance or vibrate enough, it seems, just weren’t perceived as worthy enough by the females. The findings appear December 2 in the Proceedings of the Royal Society B.
Peacock spiders have been known since the 1870s, but they have become something of a minor YouTube star in the last few years. Australian biologist Jürgen Otto, who studies mites for his day job, began filming and photographing the arachnids — an impressive achievement since the spiders are less than a centimeter in length and can move quickly. (His handiwork is in the video below.) So now all those male spiders not only have female spiders judging them but the rest of us as well.
A male Maratus caeruleus tries to gain a female’s attention. Peacockspiderman/YouTube