An act of acrobatics keeps males of one orb-weaving spider species from becoming their mates’ post-sex snack.
After mating, Philoponella prominens males catapult away from females at speeds up to nearly 90 centimeters per second, researchers report April 25 in Current Biology. Other spiders jump to capture prey or avoid predators (SN: 3/16/19). But P. prominens is unique among spiders in that males soar through the air to avoid sexual cannibalism, the researchers say.
P. prominens is a social species that’s native to countries such as Japan and Korea. Up to 300 individual spiders can come together to weave an entire neighborhood of webs. While studying P. prominens’ sexual behavior, arachnologist Shichang Zhang and colleagues noticed that sex seemed to always end with a catapulting male. But the movement was “so fast that common cameras could not record the details,” says Zhang, of Hubei University in Wuhan, China.
High-resolution video of mating partners clocked the male arachnids’ speed from around 32 cm/s to 88 cm/s, the researchers report. That’s equal to just under 1 mile per hour to nearly 2 mph.
A male Philoponella prominens spider avoids being eaten by a female after sex by leveraging hydraulic pressure to extend leg joints and fling himself away, seen here first at about one-fiftieth actual speed and then at normal speed.
The jump looks a little like the start of a backstroke swimming race, Zhang says. Males hold the tips of their front legs against a female’s body. The spiders then use hydraulic pressure to extend a joint in those legs, quickly launching a male off a female before she can capture and eat him.
Of 155 successful mating rituals that the researchers observed, 152 males catapulted to survival. The remaining three that didn’t fell victim to their partner. Female spiders also ate all 30 males that the team stopped from jumping to freedom with a paintbrush.
These male orb weavers probably acquired their jumping abilities to counter females’ cannibalistic tendencies, Zhang says. The spiders’ leap to survival is a “fantastic kinetic performance.”
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