The Tricky Business of Spider Foreplay

This sounds disturbingly like the spider equivalent of after-school special, fast-maturing male tangle-web spiders move in with young females and teach them spider foreplay. And, like all after-school specials, the males pay a terrible price for their spidery hedonism.

This is one of those animal behaviors that sounds way creepier if you've forgotten that we're actually talking about spiders, and not just some creepy older dude who hangs around the rec center or something. The University of Pittsburgh's Jonathan N. Pruitt and the University of Tennessee's Gordon M. Burghardt and Susan E. Riechert have researched the unusual social lives of Anelosimus studiosus, popularly known as the tangle-web spider.

In the abstract for their new paper, they explain just what these rowdy spider teenagers (using the term loosely) get up to:

Males mature early in the reproductive season and recruit to the webs of juvenile females and guard them until they mature. During the period before females mature, males and females engage in repeated bouts of non-conceptive (play) sexual behavior, where the pair courts and engages in mock copulation; both males and females gain performance-enhancing experience via these encounters.

In their study, the researchers examined which males and females were more likely to take part in this spider foreplay, and how it influenced their future sex lives. Here, they explain the consequences all this fooling around has for males:

High body condition males of the aggressive phenotype were more likely to engage in non-conceptive sexual behavior than males with lower body condition. Body condition did not influence docile males' propensity to engage in non-conceptive sexual behavior, but female size did. Docile males engaged in more non-conceptive sexual displays with larger females.

Engaging in non-conceptive sexual displays negatively impacted male performance in staged male–male contests for access to females. This cost was greatest for males of the aggressive phenotype, which are otherwise favored in male–male contests. Our findings indicate expression of non-conceptive sexual displays is linked to personality and results in reproductive performance trade-offs for male A. studiosus.

Basically, males who spend their early days having fun run a very real risk of losing out on actual mates later in life. Sure, they can gain lots of useful experience from this foreplay…but they may be so exhausted from it all that they've got nothing left for actual spider sex. Again, this is one of those things that sounds absolutely horrible, until you remember we're just talking about spider sex. Actually…I still feel kind of bad for those spider dudes.

Via the International Journal of Behavioral Biology. Image by Spider Joe on Flickr.