The next day they place the arena atop a laser doppler vibrometer in the lab’s soundproof recording studio. The laser beam converts vibrations in the filter paper into a digital rendering that researchers can compare side by side with other examples.



They drop a male in with the female and use a video camera and the vibrometer to record what happens.



In about 10 percent of Schizocosa ocreata mating encounters, the female immediately eats the male. The rate of cannibalism can be as high as half of the encounters in other species, so wolf spiders walk a thin line between courtship and consumption.



For a demonstration, they paired two spiders and waited. Up close, the ocreata is camouflaged with brindled brown and black fur. But the male’s forelegs are covered in thick black bristles like a dancer’s leg warmers.



With its antic mating dance, ocreata has a nickname in the lab: “the twerking spider.”



The male raises his fuzzy appendages over his head while bouncing his body and fangs on the ground to create vibrations. Generally, spiders that make the strongest vibrations have the best breeding success, Uetz said.



The researchers watched as the male began to wave his front legs and strike the filter paper.

“Here he goes,” Uetz said. “Here comes the female. Now look at her. She’s interested.”



The female cautiously approached the male and did a curtsy — a spider invitation to mate. The male frantically bounced and waved.



“Yeah, she’s excited. It’s going to happen — unless the male gets a little skittish,” Uetz said.

Despite her apparent willingness, the male ran away to the edge of the arena where he resumed his dance, this time a little less enthusiastically. The female approached again and did another pivot and curtsy but the male again backed away.



“They were close but then she reared up slightly and scared him. She’s armed and dangerous,” Uetz said. “She’s not being aggressive but he is clearly smaller than she is. He doesn’t have a lot of experience.”



After another minute of posing, the female suddenly chased the male in two frantic laps around the arena. Lallo rescued him before the encounter could turn gruesome.