This month, it’s rainy season in the Sonoran desert of Arizona and New Mexico. For many animals it’s a time to mate – a potentially dangerous enterprise for some male spiders. I’m Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History.
For the Agelenopsis Aperta spider, courtship begins when the male climbs onto a female’s web and performs an elaborate mating dance. Fred Singer, an Associate Professor of Biology at Radford University tells us what happens next.
“We’re not absolutely certain of this but it appears that the male is putting out a chemical that will make her go unconscious. She lays on her side and he will either mount her and mate with her– and they are endurance champions- anywhere from about 6 to 10 hours usually for the average mating– or else he’ll leave her and dance around for some more.”
However, sometimes the male spider doesn’t get the chance to mate. If he fails to impress the female with his dance – it may be his last dance.
“The female may, at any point in this courtship elect to attack the male. And if she attacks him, he will either escape or else she will kill him. Most of the time the female has eaten the male after she has killed him.”
Agelenopsis Apertas aren’t the only female spiders who occasionally kill and eat their spouses, but they’re among the few who do so before they mate. Doing this guarantees the female a good meal, but it also may ruin her chances of reproducing. Now, scientists still aren’t sure what the benefits of this form of cannibalism are, but it could be a variation of the time honored process of selection, where females of the species choose the most fitting mate.
Additional funding for Pulse of the Planet has been provided by the National Science Foundation. I’m Jim Metzner.