How the zebra got it's Stripes ?

  Researchers have found that the distinctive black and white stripes keep the flies away. Horseflies have been found in tests to be less attracted to zebra's stripes than to a white, brown or black horse coat. Such protection is vital, as horseflies transmit diseases.

  When a sunlight is reflected off a dark brown horse, the light waves tend to vibrate horizontally rather than vibrate in all directions as they do in sunlight or off the coat of white horses. This phenomenon is called 'linearly polarised light' and are also produced by water, where horseflies can mate and lay eggs. Originally, the zebras were black and were introduced the white stripes to destroy the signal of the reflected linearly polarised light.

Horsefly

  Further research is needed, but if the response to linearly polarised light is widespread among disease-carrying insects, then it may provide new means of protection for humans. Something dark could be used as a trap, drawing flies towards it and away from people, Otherwise, striped clothes could be worn to offer more protection against these disease-carriers.





Source : BBC Knowledge, Vol.4 Issue 6, page 16 "How the zebra got its stripes"