ambience: Crickets and lab sounds
It may not be the way you’d go about starting a family, but for the female Redback spider the key to successful mating is simple: find a male spider, mate, and then eat him! I’m Jim Metzner, and this is the Pulse of the Planet.
Redbacks are an Australian relative of Black Widows. These spiders practice a kind of sexual cannibalism: over the course of copulation, the female Redback slowly consumes her partner. But why would the female want to eat the father of her children? Well, partly because she’s hungry, and partly because, for Redback spiders, mating more than once may be more trouble than it’s worth.
“There’s all sorts of risks involved with mating. There’s the time and energy devoted to mating. In Redbacks, there’s also the fact that males hang around on the web producing vibrational courtship signals, and these signals can interfere with the females prey sensing abilities, for example. And then the male sometimes tries to steal little bites of the female’s food, essentially. So there may be costs associated with having a male on the web, trying to mate with you all the time.”
Maydianne Andrade is a graduate student at Cornell University, where she spends much of her time in a small humid laboratory filled with spiders and insects. It’s here that she’s had a chance to study the ways that female Redback spiders make the most out of a single mating.
“So in the lab, I’ve mated a female to a single male and had them produce viable offspring for the next 2 years. And they’ll lay an egg sack once every two to three weeks if they’re well fed. So, females can continue producing huge numbers of offspring from this one insemination for most of their lives.”
We’ll hear more on Redback spiders in future programs.
To hear about our new CD, please visit pulseplanet.com. Pulse of the Planet is presented by the National Science Foundation. I’m Jim Metzner.