You've no doubt heard that female black widow spiders devour their male companions after mating with them. Add to that list praying mantisses, midges, and horned nudibranches. This week,
an amusing story in the science section of the NYT explores the notion of sexual cannibalism in some detail in order to answer the question of why this peculiar phenomenon occurs in invertebrates. According to many scientists, evolutionary pressures have forced males to sacrifice themselves as food in order to nourish their future offspring's mother until birth and so have their genes passed on. There is some evidence for this, namely that during mating and subsequent cannabalization males plug the female's sperm receptable in order to prevent her from receiving sperm from other males. Moreover some male red back spiders develop a pinched abdomen before mating that is used to mitigate damage when/if they are eaten by the female. Yet some recent studies contradict the idea that males are indeed complicit in their own deaths. A group in New York did some experiments with mantisses to study the behavior of males when mating with females that were either hungry or had been recently fed. This group discovered that the males approached hungry females with much more caution obviously fearful of their pending doom while they were eager to approach their gorged counterparts. The intrigues of nature are boundless.