Male redback spiders invite cannibalism through a ‘self-sacrificial somersault’ during sex – but why?

Male redback spiders engage in a unique mating behavior where they somersault onto their female partner's mouth, effectively inviting cannibalism. This behavior, known as a "self-sacrificial somersault," has been found to have a genetic basis. Researchers compared the Australian redback spider to its non-cannibalistic cousin, the New Zealand katipō spider, by breeding the two species together.

According to ABC News AU, the study, published in Biology Letters, suggests that male redback spiders inherit this trait via sex chromosomes. The research, conducted by the University of Hamburg in Germany, sheds light on the DNA behind the self-sacrificing somersault. Bruno Alves Buzatto, a behavioural ecologist at Flinders University, described the findings as "very striking," supporting the idea that being killed during copulation and cannibalised can actually lead to the male's advantage.

Male redback spiders are monogynous, meaning they mate with only one female. They live fast and die young, ending their lives in a ritual of sexual cannibalism. The genetic data and courtship information from this study could also help conserve the related, threatened New Zealand katipō spider.

Brief written by urgent.news from The Guardian, ABC News AU, The Guardian Australia — 3 reports on this story. Machine-written — may contain errors; check the original before relying on it.