The Sex Life of Adolescent Spiders

female Steatoda spec. spiderPhoto: Andre Karwath

You might remember some pretty heavy petting sessions from your time as a youth before you were ready for more adult experiences. Well it seems some comb footed spiders get up to something similar and it has advantages for them, especially for the males!

Female comb-footed spider (family Theridiidae), Enoplognatha ovataPhoto: Bruce Marlin

Researchers have found that they have mock sex play before the female is able to mate (she has an opening that stays closed until maturity) while the male spider who matures faster, engages in a courtship display and drums on her legs, but without the sperm in his palps. If she approximates a mating position then he does as well and taps her on her abdomen where the opening will appear during the final moult.

Female black widow spider, Latrodectus sp., from La Manzanilla, Jalisco state, Mexico, eating a honey beePhoto: camazine

Scientists have discovered that spiders who had engaged in sex play before full maturity also actually had advantages. The couple proceeded to full intercourse more quickly than those who had not engaged in it. This means that another male is less likely to be able to displace him and the first one in gets to fertilize the majority of the egg case. They also found that the female invested more energy in the amount and size of her egg sacs by weight.

“I thought it would sound silly if I called my talk ‘Spider Sex Play,’” Pruitt said, “but that’s essentially what it is. ”It also carries some dangers because these females are still cannibalistic so there is the chance the male will engage in mock play and never have the opportunity to experience the real thing! Once again nature shows us that little we do is new!”

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