You don’t hear of too many insects that engage in oral sex. It is more common in the animal kingdom, but pretty rare among insects. There are only two species of spiders that engage in it and one of them is the species from Madagascar, Darwin’s bark spider. These male spiders use oral sex every time they mate with a female and they really go all out with it, having been observed performing fellatio before, during, and after sex up to 100 times.
One factor that causes species to have bizarre sexual behaviors is the size ratio between the males and females. The males of the Darwin’s bark spider are only a quarter of an inch in length, while the females generally being around four times that size. This means the males have to come up with ways to monopolize the females in order to mate with them. The males of the Darwin’s bark spider will restrain their females with silk bonds, perform intense fellatio as you just read above, and even break off “genital plugs” to prevent the female from mating with other males.
Scientists believe there are a few reasons for why these male spiders perform oral sex on their mates. They believe it is unlikely that they do this in order to prevent the female from eating them, as they do it with every female they mate with, even ones that have just molted that cannot kill them. It is more likely that they perform oral sex to prove their fitness as a potential mate. They could also do it because there are enzymes in their saliva that help the transmission of sperm and possibly reduce the success of sperm later deposited by other males. Either way one thing is clear…they don’t do it for the pleasure.
DO you know of other animals that perform fellatio? Why do they do it?