Jumping spiders buzz, thump when dancing

Science News, July 3, 2004 by S. Milius

Some jumping spiders, famed for eye-catching ornamentation and courtship dancing, have recently been recognized as accomplished vibration artists as well. New tests show that among Habronattus dossenus, a male's display--even if it's visually striking--probably won't succeed unless he sends the right seismic messages.

Jumping spiders have large eyes, which give them the look of "surprised teddy beam," says Damian Elias of Cornell University. Their bodies sport colored patterns and hair tufts, which a courting male shows off as he waves and flicks his legs during his slow approach to a female.

Visual aspects have dominated jumping-spider courtship research, but Elias decided to cheek out an old report that sound accompanies the courtship of another Habronattus species. He collected H. dossenus spiders from Arizona and took them to Andrew Masons lab at the University of Toronto. There, an extremely sensitive detector picked up vibrations that a male makes, Elias and his colleagues reported in the November 2003 Journal of Experimental Biology. "This was a whole new world," says Elias.

When a male has edged to within about a body length of the female, he starts thumping, scraping, and buzzing. The vibrations synchronize with the motions of the male's raised legs, almost as if he's snapping castanets over his head.

A male forced to display on a rock or sand tends not to interest a female, Elias reports. These substrates don't carry vibrations well. A male does better dancing on leaves, which easily pick up vibrations. Elias says he's interested in discovering how such a visual animal ended up with multimedia communications.