Sexual cannibalism in spiders and other invertebrates

Abstract A variety of animals, but most notably certain species of praying mantids, scorpions, and spiders, have gained some notoriety for attempting to consume their mates, with descriptions of this behaviour making good copy for popular articles on courtship and mating in animals. However, the evolutionary basis of this form of cannibalism has received little empirical or theoretical attention in the biological literature, and descriptions are usually anecdotal or associated with general descriptions of courtship and mating. For example, many textbooks state that cannibalism of sexual partners has been responsible for the evolution of elaborate courtship behaviour in many spiders (e.g. Manning 1972; Gould 1982; Cloudsley-Thompson 1988), despite the lack of either within-species or comparative evidence. Cannibalism of sexual partners may have been ignored in the past because it did not accord with the traditional view of courtship and mating as largely cooperative and harmonious ventures, a view that is being replaced by the idea that there are conflicts of interest between the sexes (e.g. Krebs and Davies 1987). Because cannibalism of sexual partners represents an extreme form of the conflict of interests between males and females, it offers an interesting model system for understanding animal mating and courtship behaviour.