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斑馬是黑毛白斑,不是白毛黑斑

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斑馬是黑毛白斑,不是白毛黑斑

Postby admin » Sat Aug 02, 2014 6:09 pm

http://animals.howstuffworks.com/mammal ... ripes1.htm
What Color Is a Zebra?
Genetics determine the variety of stripes in zebras. While the specific processing of determining this striping pattern isn't known, it has something to do with selective pigmentation. Melanocyte skin cells produce the pigments that color the fur. Certain chemical messengers regulate which melanocytes deliver their pigment to the zebra [source: Camazine]. Mathematical models haven't been able to accurately simulate the development of the pattern, but we do know that it takes place during the embryonic phase [source: The Development of Zebra Striping Pattern].
Speaking of stripes, that brings us to the age-old question: What color is a zebra? If you research this answer, you'll quickly discover many conflicting perspectives. But Lisa Smith, Curator of Large Mammals at Zoo Atlanta, reports that the coat is "often described as black with white stripes." This makes sense since the pattern is a result of pigment activation (black) and inhibition (white). That means black is the actual color of the fur, and the white patches are simply the areas that lack pigmentation [source: Camazine]. To top it off, most zebras have dark skin beneath their fur [source: Smith].
Although zebras share similar stripe patterns and the same general appearance, a closer examination of their coats reveals distinct differences among the three existing species:
Burchell's/plains zebras (Equus burchelli): These are the most populous zebra species, found in northern Kenya. Their broader stripes fade to gray, called shadow striping, as they move down the body. Their legs feature a lot of white as well.
Grevy's zebras (Equus greyvi): These zebras have the largest build and are found in northern Kenya as well. They have narrower stripes with definitive black stripes slicing down the middle of their backs and white bellies. Because drought and an increasing human population have severely reduced their numbers, the World Conservation Union lists Grevy's zebra as an endangered species [source: National Zoo].
Mountain zebras (Equus zebra): Found in southern Angola and Namibia, mountain zebras are the least common of the species. A square flap of skin on their throats distinguish these zebras from the other two species. They also sport wide stripes against a cream-colored background.
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