Thank you for visiting nature. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser or turn off compatibility mode in Internet Explorer. In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Several clades of spiders whose females evolved giant sizes are known for extreme sexual behaviors such as sexual cannibalism, opportunistic mating, mate-binding, genital mutilation, plugging and emasculation.

Sexual selection in spiders shows how sexual selection explains the evolution of phenotypic traits in spiders. Pre-copulatory mate choice processes have been observed in a wide range of spider species , including Stegodyphus lineatus , Argiope aurantia , Schizocosa floridana, Hygrolycosa rubrofasciata, and Schizocosa stridulans. Sexual selection occurs after copulation as well as before copulation. Sperm competition occurs when the sperm of more than one male competes to fertilize the egg of the female.

Males and females of some spider species differ hugely in size. The most extreme examples of such sexual size dimorphism are among the orb weaver spiders. For the tiny male golden orb weaver Nephila pilipes , approaching the female is fraught with peril: She can be 10 times his length and times heavier. Some spiders pair puny males with gigantic females, making mating both tricky and dangerous. Why and how such mismatches evolved remains curiously enigmatic.

Spiders are bizarre sex freaks. And you thought humans had crazy sex lives? Mounting evidence in recent years shows just how crazy spider sex is.