9.High School English Listening

Rudolph the reindeer is best known for his brightly colored rednose.
For other reindeer, however, the most colorful thingabout them is actually their eyes.
Researchers have found thatdepending on the season, the eyes of Arctic reindeer change from gold to blue.
Like many mammals, Arctic reindeer have a structure in the eye called the tapetum lucidum, TL forshort.
It sits behind the retina and reflects light back to increase the sensitivity of night vision.
The TL is also responsible for reindeer eye color changes.
During the Arctic summer, when it's always light outside, reindeer TL is gold-a color that reflectsmore light back through the retina, better enabling reindeer to see in daylight.
(This is why, by theway, many mammals have gold colored eyes.)
But when the Arctic winter sets in and darkness reigns, the TL turns blue.
The result of this is lesslight reflecting back out through the retina, making it easier for the animals to see predators in dim conditions.
The color change may be caused by shifting pressure in reindeer eyes, which stems from constantpupil dilation.
When compressed, the TL reflects shorter wave lengths of blue light which are moreplentiful during Arctic winters.
译文：
驯鹿鲁道夫以其鲜艳的红鼻子而闻名。
然而，对其他驯鹿来说，它们身上最多彩的东西实际上是它们的眼睛。
研究人员发现，根据不同的季节，北极驯鹿的眼睛会从金色变成蓝色。
与许多哺乳动物一样，北极驯鹿的眼睛里有一个结构，叫做 "明胶"，简称TL。
它位于视网膜后面，将光线反射回来，以增加夜视的敏感性。
TL也是驯鹿眼睛颜色变化的原因。
在北极地区的夏季，当外面总是光亮的时候，驯鹿的TL是金色的，这种颜色可以通过视网膜反射更多的光线，使驯鹿在白天能更好地看清。
(这就是为什么许多哺乳动物的眼睛是金色的原因）。
但当北极的冬天来临，黑暗笼罩时，TL会变成蓝色。
这样做的结果是，通过视网膜反射出来的光线减少，使动物在昏暗的条件下更容易看到捕食者。
颜色的变化可能是由于驯鹿眼睛里的压力变化造成的，这源于持续的瞳孔扩张。
当压缩时，TL会反射更短波段的蓝光，而蓝光在北极地区的冬季更为丰富。
重点词汇：
Rudolph 鲁道夫
known for 以…而闻名
brightly 明亮地，熊熊 ; 爽朗地，笑容满面地，满面春风地，神采奕奕，高高兴兴地，兴高采烈地 ; 心领神会地
change from 换下衣服 ; 使从…变成
night vision 夜视
responsible for 负责 ; 是造成…的原因