Why Is It More Advantageous For Female Spiders To Consume Male Spiders Rather Than The Other Way Around?
It has become common knowledge that several spider species indulge in sexual cannibalism. Black widows are particularly well known for exhibiting post-coital cannibalistic behaviors, but sexual cannibalism is so prevalent within the spider order of arachnids that this behavior can be considered the norm for most spider species. In addition to the spider order, most species in the scorpione order of arachnids indulge in sexual cannibalism as well. Of course, as many people are already aware, sexual cannibalism in spiders is a female behavior. The reason for this is due to the superior size and strength of female spiders relative to their male counterparts. As long as the female sex possesses the larger sized body, males will always be at the mercy of their mate’s hunger. While female sexual cannibalism among spiders is the norm, some spider species see the male indulging in sexual cannibalism. Unlike female sexual cannibalism, which is now understood to be advantageous to the survival of a species, researchers do not yet understand how male sexual cannibalism favors a species’ survival.
Although brutal, female sexual cannibalism can be an advantage for a species as a whole. For example, if food sources are low, but male suitors are abundant, then females have every reason to feed on males in order to survive, as plenty more males will still be available to transmit sperm to the female. After all, only one male is needed to impregnate a group of female scorpions (yes, scorpion females become pregnant). But if males were to eat females to the point where males outnumber females, then several males will be deprived of a chance to pass on their genes, but at least the males will be satiated. Also, male spiders fulfil their purpose after passing on their sperm to a mate. The only concern a male spider has after sperm transmission is to keep the female alive so that she can bear his offspring, and this may mean sacrificing himself as a source of sustenance to the female, which the males from many spider species have no problem doing.
Have you ever witnessed a pre-mating ritual between a male and female spider?