英語聽力文摘 天生的獵手

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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.

蛇的視力

蛇靠著它們的“熱視力”能力來在夜晚捕捉獵物。是對還是錯?

答案當然是正確的!但是把蛇的這種能力說成是“視力”好像不是很準確。更準確地說，應該是某些蛇類，如響尾蛇，在它們眼睛的下面部位有專門的呈凹陷狀的熱感應器官——頰窩。

在沙漠當中，蛇的這一能力可謂是方便之極。特別是當蛇在周圍光線不足的情況下，想要抓只小老鼠當點心的時候，更能體現(xiàn)其方便之處。響尾蛇是響當當?shù)牟东C好手，當然，這基本上是得益于它的熱感應能力。

新的研究表明，頰窩還可以用來做冷感應器。生活在沙漠中，找出較涼爽的地方也是很重要的;畢竟，在沙漠中過熱現(xiàn)象是家常便飯。兩名印第安納州立大學的研究人員在Terre Haute得出了這一結(jié)論。他們暫時用膠水把塑料小球固定在一些響尾蛇的頰窩上，以此將它們的頰窩堵住。

在頰窩被堵住的情況下，響尾蛇便無法從一個迷宮中找出“溫度較低的地方”，相比，它只會在四處亂轉(zhuǎn)。此時此刻的它們是“冷盲”。取出小塑料球，響尾蛇便能迅速地找出較冷的地方。也可以說是，他們的熱視力已經(jīng)恢復了。

目前，科學家們正就此展開討論。但是，從演化歷史來看，憑借這一能力在沙漠中找到一個較涼爽的地方確實是至關(guān)重要的。滿足這一點之后，再靠熱感應能力去抓一只活生生的老鼠也算是美味的獎勵啦。