Researchers have found that a species of wee venomless orb weaver known as Philoponella prominens uses a truly unique strategy to prevent marital disharmony. After mating, the males bounce. Literally.
P. prominens is a “social” spider. Social spiders live in communal webs that house up to 300 residents. They cooperate in web-building, prey capture, feeding, and sometimes they even share the responsibilities of brood care. After hatching, spiderlings build their own webs, connected to their mothers’. But all that pleasantry vanishes when mating season comes around.
Many species of spider have wildly lopsided sexual dimorphism, and P. prominens is no exception. That alone is enough to make courtship and mating an asymmetrical affair. But female spiders of many species often attack, kill, and even eat their mates after mating. Males of some species will rip off their own legs to distract their innamorata dentata — sometimes before mating.
It’s all a lot of violence, especially for a venomless social spider barely a quarter inch long. So, P. prominens evolved a unique solution. After two spiders have their fling, the male P. prominens will fling himself bodily away from the female as a conclusion to the mating ritual — after the meet cute, a yeet cute, if you will. During this leap, the males also spin hundreds of times a second during their backward arc, although we don’t know why. (Scientists we consulted are evenly split on whether it’s aerodynamics or pure glee.)
Leap of Faith
In the observational experiment that provided this revelation, researchers watched 155 instances of “successful spider mating.” But it takes barely four milliseconds for male P. prominens to take their leap of faith. So, Shichang Zhang and colleagues patiently recorded 155 spider sex tapes with a 1,500-fps camera.
Even that framerate, however, couldn’t assure crisp video on its own. The camera often took long enough to focus that by the time it did, the catapulting spider had already moved into a different focal depth. “Once the spider was mating, people had to adjust the equipment to focus on them,” Zhang told Smithsonian Magazine. “The spider is tiny, so most of the time, males had catapulted before the focus was ready.”
Males that don’t get away are in for a nasty end. P. prominens doesn’t have venom; they “mummify” their prey in silk. But a female’s suitors aren’t exempt from this aggression. Female P. prominens will snare and mummify their own mates after coitus. They wrap their captives so tightly their legs break, crushing or suffocating the hapless victim. Out of 155 mating events, only three males didn’t fling themselves away. Every male who did, survived. All three who didn’t were eaten.
Hydraulics
The males of this species prepare for their quantum leap by folding in their two forelegs like a jackknife. Then they brace their folded forelegs against the bodies of their mates. Female P. prominens are twice the size of males, which makes this more plausible as a means of escape. Zhang compared the position to a backstroke swimmer, folded up and braced against the side of the pool.
A wild nope appears: Depicted here are two Philoponella prominens spiders mating. Image: Shichang Zhang
As for how they actually make their leap, it’s all hydraulics. Spiders don’t have a muscle that they use to extend their legs. Instead, “Spiders have a big muscle in their thorax and when they compress it they can shoot their body fluid into their legs and cause them to straighten really fast,” said Jonathan Coddington, the Smithsonian’s curator of Arachnida and Myriapoda. Instead of a post-coital nap, the male P. prominens quickly extends its legs, catapulting itself away.
“Jumping spiders use their back four legs to jump, what’s odd about these guys is that the males are using their first pair of legs to shoot themselves into the air,” said Coddington, who was not involved in the study, in an interview. “This is surprising to see in an orb weaver.”
Indeed, not all jumping spiders are created equal, nor do they have the same advantages. But hope springs eternal in the spider brain. Male P. prominens even create a silken “tether” that they fix to the edge of their chosen female’s web before making an overture. If they manage to make their aerial escape, some masochistic males climb right back up the waterspout to try, try again.
The paper appears in this week’s issue of Current Biology.
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