Sometimes female spiders eat their mates after mating. The males of one species found a great escape route.
The praying mantis does this, and so do the females of some species of beetles, but spiders in particular are known for this: sexual cannibalism is a reproductive strategy. The female eats the male after or during mating. It was still able to reproduce and receive energy and nutrients to produce eggs. The investment of the male’s body and life serves his successful reproduction.
Best for him and for the survival of his genes is to have more than one chance to do so. It can produce more offspring, which should support the development of appropriate behavior and body traits for flight after mating.
Males of spider species have a special mechanism Philoponella prominens developed, has now been reported by an international research team in the journal “Current Biology.” After pollination, it flies with its front legs to safety. She missed a meal, but the female spider’s ability to take off in a flash can at least serve as evidence that she’s chosen a decent mate.
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A very quick escape from cannibalism
A research team led by Shichang Zhang from Hubei University in Wuhan, China, studied partner selection in this type of spider. Unusually for spiders, animals live in communities of up to 300 individuals in a network complex with many individual networks. “We’ve noticed that mating ends with a catapult trip so fast that conventional cameras can’t clearly record the details,” Zhang says.
Using high-resolution video cameras, the team determined an average speed of about 65 centimeters per second for catapult male spiders. Some of them are nearly 90. It accelerated at a rate of 200 meters per second, which is roughly equivalent to the acceleration of a professional cyclist. Thus spiders achieve higher values than missiles, roller coasters and airplanes in aerial maneuvers.
Males use a mechanism that has not yet been described. They fold over a joint of their front legs and press the female with their bent legs. The researchers explained that there are no extensor muscles in Spider-Man for this joint, but hydraulic pressure builds up, causing them to suddenly open when Spider-Man disengages.
In the animal world there are other examples of such attraction mechanisms, in which energy is stored slowly, which then allows for very rapid actions or reactions, similar to operating a catapult. The praying mantis, for example, uses its front legs to catch prey. Snapjaw ants also lock their jaws to jump away from predators. “However, such ultra-rapid procedures as a means of avoiding sexual cannibalism have not yet been reported,” the researchers wrote.
Choosing the right partners
After 155 instances of notable mating, nearly all of the males jumped from the females in this way and survived. Only three males did not attempt to escape. They are caught and eaten by females. This is exactly what happened to male spiders, as scientists blocked the jumping mechanism with a thin brush. In 30 trials, the females ate it all. These results clearly indicated that ejaculatory behavior was a critical component of mating behavior in males. The spider-woman’s bite avoidance strategy evolved under powerful female predatory pressure – the carnivores of their sexual flesh.
“Females may use this behavior to judge the quality of the male during mating,” Zhang suspects. If the male cannot catapult, they kill him. If he repeatedly manages to make an amazing escape, then the animals mate up to six times, accepting him as a partner.
In future studies, the team wants to investigate the role of ejaculatory capacity in male mating success.