Earth and Sky【23】

Spiders give many of us the shivers, though they usually leave people alone. Sometimes these spectacular predators instead prey on each other. Learn more about when spiders serve themselves as dinner —— today on EarthandSky.

　　JB: This is Earth and Sky. We recently visited the Austin Children's Museum in Texas to record your science questions. Here's one from Ben Rosselet.

　　Ben Rosselet: Why does a black widow kill its husband after it helps make babies?

　　DB: Ben, another way to think of this is to ask,"Why do some males allow themselves to be killed by females?" Some scientists think it's common for female spiders to try to eat males either before or after mating. Since spiders are zealous predators, females might unintentionally prey on males .

　　JB: Then there's the Australian red back widow —— a species of black widow. Dr. Maydianne Andrade of the University of Toronto at Scarborough found that males only have a slim chance of finding future mates, and about 80% perish unsuccessfully in the process. Indeed, it's so critical for them to mate with the first female they encounter, that males have actually evolved self-sacrifice behaviors.

　　DB: After mating begins, the male red back somersaults around, launching his tasty abdomen directly into the jaws of the female. Meanwhile, as he's being eaten, he fertilizes the female.

　　DB: It turns out that for the Australian red back widow, males that are wholly consumed are more successful at mating and father more baby spiders than those that aren't. And that's our show for today. With thanks to the National Science Foundation, we're Block and Byrd for Earth and Sky.