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Reindeer Eyes
Rudolph the reindeer is best known for his brightly colored red nose. For other reindeer, however, the most colorful thing about them is actually their eyes. Researchers have found that depending on the season, the eyes of Arctic reindeer change from gold to blue.
Tapetum Lucidum
Like many mammals, Arctic reindeer have a structure in the eye called the tapetum lucidum, TL for short. 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 reflects more light back through the retina, better enabling reindeer to see in daylight. (This is why, by the way, many mammals have gold colored eyes.)
When Darkness Reigns
But when the Arctic winter sets in and darkness reigns, the TL turns blue. The result of this is less light 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 constant pupil dilation. When compressed, the TL reflects shorter wavelengths of blue light which are more plentiful during Arctic winters.
馴鹿的眼睛
魯?shù)婪蝰Z鹿的特征就是紅彤彤的鼻子。然而，其他馴鹿身上最”出彩”的地方，則是他們的眼睛。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{色。
反光膜
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。它位于視網(wǎng)膜后，其功能是反射光線，以增強眼睛夜間視物的敏感性。馴鹿的眼睛會變色就是因為反光膜。
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，使馴鹿在白晝時的視物性更好。（順便說一句，這也是為什么許多哺乳類動物的眼睛是金色。）
當黑暗籠罩大地
但當北極的冬季來臨，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色。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。
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。反光膜在受到壓迫時會反射較短波長的藍光，這種光在北極的冬天到處都是。
【本譯文由普特網(wǎng)友 veroniquelj 提供】
PS：Tapetum Lucidum 別名：脈絡膜反光毯，脈絡膜照膜，照膜，透明絨氈層。該組織存在于人類以外的諸多脊椎動物的眼球中，呈薄膜狀，一般位于視網(wǎng)膜后方、構(gòu)成眼球脈絡膜的中層，也有部分動物的明毯直接存在與視網(wǎng)膜中。其功能是將可見光反射給視網(wǎng)膜、使光線增強以利于光感受器的接收。明毯能極大地提高一些哺乳動物的夜視能力，該組織對于夜行動物、尤其是肉食動物的生存起著至關(guān)重要的作用。除了原猴亞目的動物具有明毯外，人類和其他靈長類均不具備該組織。
Reindeer Eyes
Rudolph the reindeer is best known for his brightly colored red nose. For other reindeer, however, the most colorful thing about them is actually their eyes. Researchers have found that depending on the season, the eyes of Arctic reindeer change from gold to blue.
Tapetum Lucidum
Like many mammals, Arctic reindeer have a structure in the eye called the tapetum lucidum, TL for short. 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 reflects more light back through the retina, better enabling reindeer to see in daylight. (This is why, by the way, many mammals have gold colored eyes.)
When Darkness Reigns
But when the Arctic winter sets in and darkness reigns, the TL turns blue. The result of this is less light 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 constant pupil dilation. When compressed, the TL reflects shorter wavelengths of blue light which are more plentiful during Arctic winters.
馴鹿的眼睛
魯?shù)婪蝰Z鹿的特征就是紅彤彤的鼻子。然而，其他馴鹿身上最”出彩”的地方，則是他們的眼睛。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{色。
反光膜
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。它位于視網(wǎng)膜后，其功能是反射光線，以增強眼睛夜間視物的敏感性。馴鹿的眼睛會變色就是因為反光膜。
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，使馴鹿在白晝時的視物性更好。（順便說一句，這也是為什么許多哺乳類動物的眼睛是金色。）
當黑暗籠罩大地
但當北極的冬季來臨，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色。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。
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。反光膜在受到壓迫時會反射較短波長的藍光，這種光在北極的冬天到處都是。
【本譯文由普特網(wǎng)友 veroniquelj 提供】
PS：Tapetum Lucidum 別名：脈絡膜反光毯，脈絡膜照膜，照膜，透明絨氈層。該組織存在于人類以外的諸多脊椎動物的眼球中，呈薄膜狀，一般位于視網(wǎng)膜后方、構(gòu)成眼球脈絡膜的中層，也有部分動物的明毯直接存在與視網(wǎng)膜中。其功能是將可見光反射給視網(wǎng)膜、使光線增強以利于光感受器的接收。明毯能極大地提高一些哺乳動物的夜視能力，該組織對于夜行動物、尤其是肉食動物的生存起著至關(guān)重要的作用。除了原猴亞目的動物具有明毯外，人類和其他靈長類均不具備該組織。