在线英语听力室_免费在线英语听力学习网站

　　This is Scientific American's 60-Second Science. I'm Christopher Intagliata. Got a minute?
Toss a piece of leaf onto a spider web. The spider is indifferent. Because leaves don't squirm like captured flies. But Australia's "assassin bug¹" turns the tables on spiders. It exploits their keen sense for vibrations² by mimicking⁴ the movements of prey⁵—luring unwitting spiders into striking range.
Researchers observed how spiders reacted to various visitors to their webs—like leaf fragments, courting males, prey like flies and the assassin bugs⁶. The spiders ignored leaves, and assumed mating position for males. But they approached assassin bugs just as if they were investigating a juicy fly.
Then the researchers analyzed⁷ the frequency, duration and amplitude⁸ of each visitor's vibrations. And they found that assassin bug's vibes most closely matched some of those of prey. When prey struggle violently, spiders rush to subdue⁹ them—a potentially dangerous situation for assassin bugs. So the bugs have learned to gently pluck the silk strands¹⁰, to mimic³ only the unthreatening leg twitches¹¹ of exhausted¹² prey. The research is in the journal Proceedings¹³ of the Royal Society B.
The assassin bug's choice of vibrations maximizes the chances that the spider, while still behaving like the hunter, becomes the hunted.
Thanks for the minute. For Scientific American's 60-Second Science, I'm Christopher Intagliata.