【英语时差8,16】巨大的声响(在线收听

Ya?l: On today's Moment of Science: The praying mantis, an auditory Cyclops.
D: Sounds like a B-Movie from the 1950's!
Y: To small insects, praying mantids probably do seem like something out of a monster      movie. Mantids are some of the most impressive insect predators, regularly snaring      other insects or even the occasional lizard, snake or frog.
     But despite their hunting skills, mantids are ill-equipped to avoid predation      themselves. Camouflage keeps some well hidden from visual hunters such as birds,      but matching the color of your background won't hide you from nocturnal predators,      like bats. Many bats locate their prey in total darkness by echolocation---producing      ultra-high pitched calls and listening to the reflections, or echoes off objects in their      environment.
D: I thought this show was about the praying mantis?
Y: Right. Praying mantids were long thought to be deaf, but neuroscientists at Cornell      and the University of Maryland discovered a single teardrop-shaped ear along the      middle of praying mantis' thorax. Praying mantids don't produce sounds, and don't      use sound to locate their prey, so why would they need to hear?
D: Bats?
Y: Bats. The researchers tested whether the mantids' unique ear could hear the      ultrasonic cries of bats, which are too high pitched for human ears to detect. When      the scientists played recordings of bat echolocation calls to free-flying mantids, the      mantids abruptly stalled in the air and erratically spiraled downward, dropping out of      the sky. The evasive maneuvers enable a normally slow-flying mantids to escape bat      attacks in nearly eighty-percent of trials. When scientists deafened the mantids, they      only escaped bat attacks thirty-four percent of the time. So ultrasonic hearing gives      mantids a huge advantage.
D: And the one-eared mantis lives to hunt another day!  
  原文地址:http://www.tingroom.com/lesson/englishtimeover/335482.html