Monday, 5 March 2012

What Is A Line? Striped Animal Research.

'Barcode' Scanner identifies striped animals.

Are Zebras black with white stripes or black with white stripes?

Zoologists have yet to unravel all of the genetic mysteries that lie behind the zebra's signature striped suit. The alternating color pattern works well with its native environment, deflecting up to 70 percent of the heat that hits its body. The arrangement of the stripes adds another intriguing dimension to the animal's biology since each zebra has a completely unique design. In particular, the stripes on its shoulders, or withers, contain the most individualized markings.
If you wear a zebra-print outfit in a crowd, it nearly guarantees that someone will easily spot you. In the jungle, however, a zebra's stripes actually work as a camouflage to deter its main predators: lions and hyenas. Since the animals herd together, experts believe that the mass of stripes can confuse the predators by acting as an optical illusion that blends their figures together. Consequently, a group of 10 zebras may look like a giant striped blob that a lion wouldn't want to take on solo.



How do a zebras stripes act as camouflage?

To humans, a zebra's stripes stick out like a sore thumb, so it's hard to imagine that the stripes act as camouflage. Zoologists believe stripes offer zebras protection from predators in a couple of different ways.
The first is as simple pattern-camouflage, much like the type the military uses in its fatigue design­. The wavy lines of a zebra blend in with the wavy lines of the tall grass around it. It doesn't matter that the zebra's stripes are black and white and the lines of the grass are yellow, brown or green, because the zebra's main predator, the lion, is colorblind. The pattern of the camouflage is much more important than its color, when hiding from these predators. If a zebra is standing still in matching surroundings, a lion may overlook it completely.
This benefit may help an individual zebra in some situations, but the more significant means of protection has to do with zebra herds. Zebras usually travel in large groups, in which they stay very close to one another. Even with their camouflage pattern, it's highly unlikely a large gathering of zebras would be able to escape a lion's notice, but their stripes help them use this large size to their advantage. When all the zebras keep together as a big group, the patte­rn of each zebra's stripes blends in with the stripes of the zebras around it. This is confusing to the lion, who sees a large, moving, striped mass instead of many individual zebras. The lion has trouble picking out any one zebra, and so it doesn't have a very good plan of attack. It's hard for the lion to even recognize which way each zebra is moving: Imagine the difference in pursuing one animal and charging into an amorphous blob of animals moving every which way. The lion's inability to distinguish zebras also makes it more difficult for it to target and track weaker zebras in the herd.
So do zebra stripes confuse zebras as much as they confuse lions? Oddly enough, while making zebras indistinguishable to other animals, zebra stripes actually help zebras recognize one another. Stripe patterns are like zebra fingerprints: Every zebra has a slightly different arrangement. Zoologists believe this is how zebras distinguish who's who in a zebra herd. This certainly has significant benefits. A zebra mare and her foal can keep track of each other in the large herd, for example, and a zebra can very quickly distinguish its own herd from another. This also helps human researchers, because it enables them to track particular zebras in the wild.
Animal Coat Pattern Formation
 The importance of mathematics in certain fields such as physics has been known for a long time but recently its power has also been discovered in biology. Some phenomena that one believed to be owing to chance or to the action of genes are revealed to be the consequence of mathematical dynamics. Perhaps the most spectacular example is that of the pattern on the coats of animals.
Why are the coats of certain types of animals such as the leopard spotted, whereas the coats of others are striped (tiger, zebra). Why are the spots of the giraffe much bigger than and different from those of the leopard? Why do certain animals, such as the mouse and elephant not have a pattern? Why do some animals, such as the cheetah, jaguar, leopard and genet, have spotted bodies and striped tails, but there are no animals with striped bodies and spotted tails?
All of these questions now have a mathematical answer. The model in question describes the way in which two different chemical products react and are propagated on the skin : one which colors the skin, and one which does not color it; or more precisely, one which stimulates the production of melanin (coloring the skin) and one which inhibits this production.
What is remarkable is that the equations show that the different patterns of coat depend only on the size and form of the region where they are developed. Stated in another way, the same basic equation explains all of the patterns. But then, why do the tiger and the leopard have different patterns given that their bodies are similar? This is because the formation of the patterns would not be produced at the same moment during the growth of the embryo. In the first instance, the embryo would be still small and in the other, it would be at a much bigger stage.


Why do tigers have stripes?

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