How not to end up being the female’s dessert after intercourse. This is the goal of the male spider species Philoponella prominens which, in a previously unobserved mechanism, male spiders use a joint in their first pair of legs to immediately undertake a split-second catapult action, hurtling away from their partners at impressive speeds of up to 88 centimeters per second.
High-resolution video of mating partners recorded the speed of the male arachnids from about 32 cm/s to 88 cm/s , the researchers report.
“We found that mating always ended with a catapult, which is so fast that ordinary cameras couldn’t record the details clearly,” explains co-author Shichang Zhang of Hubei University in Wuhan, China .
postcoital catapult
For male orb-weaver spiders, making a quick exit after mating is a matter of life and death. If they didn’t run away, the females would kill and eat them.
The highly unusual strategy is described in a paper published in Current Biology , which explores how they use their first pair of legs to dart away from their mates to safety the moment they’re done. This acrobatic act prevents the males from becoming their mate’s snack.
The species and its behavior
Philoponella prominens is a social species that is native to countries like Japan and Korea. They belong to a family of spiders that do not contain poison.
Up to 300 individual spiders can come together to spin an entire neighborhood of webs. While studying the sexual behavior of this species, arachnologist Shichang Zhang and colleagues noticed that sex seemed to always end with a catapulted male. But the movement was “so fast that ordinary cameras couldn’t record the details,” says Zhang, of Hubei University in Wuhan, China.
Using high-resolution video cameras, the researchers calculated an average maximum speed of catapulting spiders of approximately 65 cm/s. Velocities ranged from about 30 cm/s to almost 90 cm/s. As they soar through the air, the males also spin around 175 times per second on average.
The few males the researchers saw that did not catapult were quickly captured, killed, and consumed by their female mates. When the researchers prevented the males from catapulting, they met the same fate. Of 155 successful matings, they found that 152 ended with the male being catapulted and saving his life. All of those catapulted males survived their sexual encounters.
“We observed that males that couldn’t catapult themselves were cannibalized by the female,” says Zhang. “It suggests that this behavior evolved to fight sexual cannibalism by females under strong predation pressure from females. Females can use this behavior to judge the quality of a male during mating. If a male can’t catapult himself, he kills him, and if he can run away multiple times, then he accepts his sperm.”
The scientists say the findings clearly show that the behavior of catapulting is necessary to prevent sexual cannibalism. These male orb-weavers likely acquired their jumping abilities to counter the cannibalistic tendencies of the females, Zhang says. The spiders’ jump to survival is a “fantastic kinetic performance.”
Referencia: “Male spiders avoid sexual cannibalism with a catapult mechanism” by Shichang Zhang, Yangjié Liu, Yubing Ma, Hao Wang, Yao Zhao, Matjaž Kuntner and Daiqin Li, 25 April 2022, Current Biology. DOI: 10.1016/j.cub.2022.03.051
