英语听力文摘 English Digest 414、天生的猎手（在线收听）

Snake Vision

Snakes have heat-vision that allows them to catch their dinners in the dark. True or false?

True! It isn’t quite right to call it “vision,” though–more accurate would be to say that certain species, such as rattlers, have pits just under their eyes that contain specialized heat-sensing organs.

This ability to spot heat comes in handy in the desert, especially if you’re out looking for a quick-moving mouse to make into a snack and there isn’t enough light to see by. Rattlers are amazingly good at catching prey because of their heat-seeking ability.

New studies have actually shown that the same sense organs are used for seeking cold as well. This is just as important when you live in a desert; overheating is always a possibility. Two researchers at Indiana State University in Terre Haute found this out by covering some rattlers’ facial pits with little plastic balls temporarily glued in place.

With these organsblocked, the rattlers were no better at finding the cool spot in a maze than if they had been moving around by chance. They were “cool-blind.” Take the balls out and the rattlers quickly found their way to the cooler spot. Their thermal vision, so to speak, had been restored.

Now researchers debate this, but it’s possible that the ability to find a cool spot in a desert actually came first, in terms of evolutionary history. Get that, and the ability to snag a hot mouse might come as a tasty bonus.

蛇的视力

蛇靠着它们的“热视力”能力来在夜晚捕捉猎物。是对还是错？

答案当然是正确的！但是把蛇的这种能力说成是“视力”好像不是很准确。更准确地说，应该是某些蛇类，如响尾蛇，在它们眼睛的下面部位有专门的呈凹陷状的热感应器官——颊窝。

在沙漠当中，蛇的这一能力可谓是方便之极。特别是当蛇在周围光线不足的情况下，想要抓只小老鼠当点心的时候，更能体现其方便之处。响尾蛇是响当当的捕猎好手，当然，这基本上是得益于它的热感应能力。

新的研究表明，颊窝还可以用来做冷感应器。生活在沙漠中，找出较凉爽的地方也是很重要的；毕竟，在沙漠中过热现象是家常便饭。两名印第安纳州立大学的研究人员在Terre Haute得出了这一结论。他们暂时用胶水把塑料小球固定在一些响尾蛇的颊窝上，以此将它们的颊窝堵住。

在颊窝被堵住的情况下，响尾蛇便无法从一个迷宫中找出“温度较低的地方”，相比，它只会在四处乱转。此时此刻的它们是“冷盲”。取出小塑料球，响尾蛇便能迅速地找出较冷的地方。也可以说是，他们的热视力已经恢复了。

目前，科学家们正就此展开讨论。但是，从演化历史来看，凭借这一能力在沙漠中找到一个较凉爽的地方确实是至关重要的。满足这一点之后，再靠热感应能力去抓一只活生生的老鼠也算是美味的奖励啦。