The praying mantis has been known to devour males after they have had sex. But these are not the only arthropods that resort to sexual cannibalism. For example, some do spiders. In some species they do this so frequently that males have developed a method of fleeing in terror once copulation is over using their front legs like a catapult.
And it does it so fast that so far no scientist has noticed it. However, when a group of researchers from Hubei University studied sexual selection in spiders Philoponella eminent They were able to first detect these catapult jumps, and then very accurately record and analyze them.
They noticed that the male moves away from the female at a speed of up to 88 centimeters per secondwith accelerations up to 200 m/stwo and loop units 175 rpm on average. In addition, they use their own female body to boost himself once his mission is completed. This is an interesting mechanism, which, no doubt, will please the male praying mantis.
spider catapult
Philoponella eminent This spider is from Japanwhich can also be found in Korea, Taiwan and China.
It is known for living in communal groups of around 300 individuals that form webs, some of which are linked to others. As far as their mating is concerned, hardly any behavior sexual cannibalism. However, when the authors of the study just published in Current biology saw the jump of the catapult of these spiders, everyone understood.
Of 155 matings observed, 3 males that did not use their leg catapult died, being eaten by the females.
They observed a population in which there were 155 matings. Of these, 152 males survived. 3 that were eaten by the female. And, curiously, those who survived did so because they were separated from her in just a split second after the end of copulation.
To test if this was indeed the cause, the researchers made a new observation, this time under controlled conditions. Thirty males were not allowed to jump and were all immediately eaten. It was clear that this curious jump was his only life saving method.
Therefore, they decided to analyze it in more detail. For this we used high definition cameraswith which they saw that the jumps occurred at speeds in the range from 30 cm/s to 88 cm/s. For this they used as a catapult tibiometatarsal joint its front pair of legs. They dont have extensor muscles, but they do not need them, because they use the female’s own body for movement. This way they can leave just as their work is done and avoid sexual cannibalism. Either they catapult themselves or they catapult the female.
no chase
Seeing the wide range of ejection jump speeds, one might think that slower males are amenable to jumping. pursuit of females.
However, there appears to be no such persecution. In fact, the authors of this new study suspect that such behavior serves selection method male for spiders. If someone knows how to jump, it is worth keeping him alive and crossing with him in the future. On the other hand, if he doesn’t, they decide to kill themselves, they will find better sperm. As sadistic as it is addictive.
Source: Hiper Textual
