Why do female spiders 'play dead' during mating?
In some creatures, such as spiders and praying mantises, the female eats the male after mating, and the male spider, who cannot bear to be eaten, has a clever '
Please note that this article contains images of spiders, so if you are afraid of spiders, please be careful.
Females adopt sexual catalepsy to facilitate mating | Current Zoology | Oxford Academic
https://doi.org/10.1093/cz/zoad010
Female spiders play dead during sex so males don't have to worry about being eaten | Live Science
The funnel-web spider Aterigena aculeata, which lives in
Aterigena aculeata is known to practice 'sexual cannibalism,' in which females eat males after mating. One theory is that females repeatedly mate with superior males that can escape predation, and eat males that cannot escape, thereby assessing the quality of their mates. However, males, whose lives are at risk every time they mate, are forced to be cautious about mating.
On the other hand, previous observations have revealed that females of Aterigena aculeata exhibit a behavior called 'sexual catalepsy,' in which they curl their legs and become immobile as if they were dead during mating. By immobilizing the female as if she were dead, the male can concentrate on mating without worrying about being eaten, but it was unknown whether this was because the male immobilized the female in some way, or whether the female pretended to be dead for the male.
The research team then conducted a study in which they froze and crushed females in liquid nitrogen immediately after they had experienced sexual catalepsy, females that had been shaken in a test tube to induce
Below, A is a female Aterigena aculeata in a normal state, B is a female in a state of sexual catalepsy, C is a female asleep under anesthesia, and D is a female in a state of thanatosis.
If the chemical makeup of the cataleptic female is similar to that of the anesthetized female, it would mean that the male is putting her to sleep in order to mate with her. On the other hand, if it is the same as that of the thanatotic female, it would mean that the female was faking her own death in order to mate with the male.
Analyses showed that females with sexual catalepsy were nearly identical to females in thanatosis, strongly suggesting that sexual catalepsy is a female-driven phenomenon.
'Spiders only mate if the female is in a state of sexual catalepsy, so if she doesn't do this, mating will not proceed,' said Mark Elgar of the University of Melbourne in Australia, co-author of the paper that published the study.
Furthermore, even if a male mates with a female who appears to be dead due to sexual catalepsy, he knows that she is asleep because after mating, he steps back and runs away as soon as the female wakes up.
According to Elgar, female Aterigena aculeata are not the only species that experience sexual catalepsy. This study has shown that female Aterigena aculeata are likely to experience spontaneous sexual catalepsy, but it is not yet clear whether this is the case in other species.
'It is not yet clear whether this evolved as a mate selection mechanism for females, or as a protection mechanism for males against cannibalism,' Elgar said.
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