(Astigan.com) — Spiders have a varying menu, sometimes the male spiders get eaten by their female mates. New research in this matter suggests that the answer for sexual cannibalism in spider species is correlated to the size differences between males and females.

There are various theories that try to explain sexual cannibalism within and among spider species. One theory suggests that females eat their mates because they are simply hungry and are in need of food. Another assumption is that the females often mistake their mates for prey. The sexual selection theory says that females choose their partners and eat the undesirable mates.
“Sexual cannibalism occurs in most species of spiders to a varying degree. Our research is important because it is one of the first papers to test why sexual cannibalism occurs more often in some species than others”, Dr. Shawn Wilder told Astigan.

Shawn Wilder and Ann Rypstra from Miami University in Ohio found that in one spider species, Hogna helluo, males end up meals for their female partners quite often. The research discovered that when males were smaller they were consumed by their female partners 80 per cent of the time, while larger males were never consumed.

“The frequency of sexual cannibalism in a given species of spiders is a function of the size dimorphism between males and females in that species. If males are really small compared to females then they are more likely to be eaten by females”, Dr. Wilder said.

“Our research suggests that one major factor affecting how often female spiders consume their mates is the size difference between males and females, as our research shows. Another major factor that has been shown to affect sexual cannibalism is female hunger”, he added.

However, the balance of size between male and female spiders is equilibrated. Scientists say that females will not become larger to consume more males because each smaller mate would represent just a small meal and the males would not become smaller because that would mean that they are just breakfast and would not get to mate often.

Image: A female wolf spider, Hogna helluo, consuming a male.
Credit: Dr. Shawn Wilder

Tags: miami, sexual cannibalism, size dimorphism, spiders