Sex games: A related species of Evarcha jumping spider. E. culicivora is thought to be the only animal that selects its mosquito prey based on what the prey has just eaten. This is just one of many unusual characteristics of the species.

Credit: Wikipedia

Related articles

• Spiders sacrifice genitals to ensure paternity
• Female chimps keep quiet about sex
• Free loving mums have healthier babies
• Females work harder than males
• Women have always outlived men

PARIS: From post-coital cannibalism to lust at first sight, the sex life of the African jumping spider is full of surprises, says a new study.

Researchers have discovered that while virgin females of Evarcha culicivora – which dine on blood-filled mosquitos – are attracted to mates who are meatier, if they survive the sex unscathed, they subsequently switch to partners smaller than themselves.

Post-sex snack

"It is as though females start out prepared to take the risk in choosing larger males," knowing they may be eaten as a post-sex snack, said Simon Pollard, biologist and lead author of the study at the Cantebury Museum in Christchurch, New Zealand. "And then, once mated, they become less inclined to take the risk again."

In this and other ways, the jumping spider, native to Kenya, is in a class of its own when it comes to sex. For starters, both males and females play a roughly equal role in choosing partners, and cannibalising each other. This is an aberration in the eight-legged world of arachnids, where females more typically consume their male partners.

In a series of laboratory experiments, detailed in the journal Ethology, Pollard showed that in three of four possible scenarios, an individual E. culicivora preferred a partner with an extra millimetre or two on its frame.

Virgin females, along with both experienced and inexperienced males, were all more than twice as likely to opt for a meatier mate. But females that had copulated once before saw things differently: two out of three made a bee-line for the smallest male in sight.

"Safer sex"

Exactly why experienced females prefer to practice "safer sex" only the second time around, said Pollard, "is currently unknown." Researchers are also unsure of the evolutionary benefit of males consuming females post-mating – and therefore spoiling their chances of passing their genes on.

Another finding that surprised the researchers behind the study is that E. culicivora spiders, which are armed with eye-sight "unrivalled by other animals in their size range", appear to pick their partners based on looks and size alone.

The species also has a keen sense of smell and uses that to help discern mosquitos (Anopheles gambiae) filled with vertebrate – often human – blood, from those that have an empty stomach.