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Rudolph the reindeer is best known for his brightly colored rednose.
魯?shù)婪蝰Z鹿最大的特征就是紅彤彤的鼻子。
For other reindeer, however, the most colorful thing about them is actually their eyes.
然而，其他馴鹿身上最”出彩”的地方，則是他們的眼睛。
Researchers have found that depending on the season, the eyes of Arctic reindeer change fromgold to blue.
研究人員發(fā)現(xiàn)，隨著季節(jié)的轉(zhuǎn)變，北極地區(qū)馴鹿的眼睛會從金色變?yōu)樗{(lán)色。
Like many mammals, Arctic reindeer have a structure in the eye called the tapetum lucidum, TL forshort.
同許多哺乳動物一樣，北極地區(qū)馴鹿的眼睛里有一個叫做反光膜的組織，簡稱TL。
It sits behind the retina and reflects light back to increase the sensitivity of night vision.
它位于視網(wǎng)膜后，其功能是反射光線，以增強(qiáng)眼睛夜間視物的敏感性。
TheTL is also responsible for reindeer eye color changes.
馴鹿的眼睛會變色就是因?yàn)榉垂饽ぁ?/p>
During the Arctic summer, when it's always light outside, reindeer TL is gold—a color that reflectsmore light back through the retina,
北極夏季會出現(xiàn)極晝現(xiàn)象，陽光無時無處不在，此時馴鹿眼中的反光膜呈金色，這種顏色可反射更多透過視網(wǎng)膜的光線，
better enabling reindeer to see in daylight.
使馴鹿在白晝時的視物性更好。
But when the Arctic winter sets in and darkness reigns, the TL turns blue.
但當(dāng)北極的冬季來臨，出現(xiàn)極夜現(xiàn)像，黑暗籠罩大地時，馴鹿眼中的反光膜會變成藍(lán)色。
The result of this is lesslight reflecting back out through the retina, making it easier for the animals to see predators in dimconditions.
此時，透過視網(wǎng)膜，反射出去的光會減少，對于動物來說，這樣可以使他們在光線不佳的情況下，更容易看見獵物。
The color change may be caused by shifting pressure in reindeer eyes, which stems from constantpupil dilation.
馴鹿的眼睛會變色可能是馴鹿眼睛受到的壓力發(fā)生改變所致，壓力源自瞳孔不斷放大。
When compressed, the TL reflects shorter wavelengths of blue light which are moreplentiful during Arctic winters.
反光膜在受到壓迫時會反射較短波長的藍(lán)光，這種光在北極的冬天到處都是。
