Giving Your All; October 1995; Scientific American Magazine; by Mukerjee; 1 Page(s)

That female spiders of the species Latrodectus mactans sometimes eat the male after copulation has been known since the 1930s, causing them to be called black widows. But in the case of L. hasselti, otherwise known as the Australian Redback spider, the male is even more likely to be eaten--apparently because he asks for it. In 1992 Lyn M. Forster of the University of Otago in New Zealand observed that after the male inserts one of his two sexual organs (or emboli) into the female, he backflips onto her jaws. Copulation proceeds while she slowly masticates his abdomen and injects enzymes. At the end of a possible second copulation, the male is already half-digested, whereupon the female wraps him in silk and concludes her repast.

Ethologists have since wondered what end might be served by such an extreme antisurvival trait. The male spider has no more than 2 percent of the female¿s mass and so cannot offer much nutrition to his offspring; in the 35 percent of cases in which the female refuses to eat the male, she lays the same number and weight of eggs.