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Scientists find out why zebras have stripes

Researchers with a horse in a zebra coat. Credit: School of Biological Sciences, University of Bristol

There are no flies on a zebra thanks to the evolution of their black and white stripes, according to scientists at the University of Bristol.

Researchers set out to find out why zebras have their distinct black and white skin, the answer being that it acts as a fly repellent.

The study was based around horse flies, which shows the blood-sucking parasites failing to slow down when they get near to zebras due to them being dazzled by the stripes, meaning they cannot land on the equine.

This does not happen with domestic horses, which are without stripes.

A zebra being studied. Credit: School of Biological Sciences, University of Bristol

Professor Tim Caro, Honorary Research Fellow from the University of Bristol's School of Biological Sciences, said: "Horse flies just seem to fly over zebra stripes or bump into them, but this didn’t happen with horses. Consequently, far fewer successful landings were experienced by zebras compared to horses."

Dr Martin How, Royal Society University Research Fellow in the School of Biological Sciences, added: "This reduced ability to land on the zebra’s coat may be due to stripes disrupting the visual system of the horse flies during their final moments of approach.

"Stripes may dazzle flies in some way once they are close enough to see them with their low-resolution eyes."

To prove their point, the academics dressed up a domestic horse as a zebra, to show fewer flies land on them.

In Africa horse flies can carry disease, and a bite can be fatal for a zebra, so they have need to evolve to avoid the insects.

It is hope the research will help the horse industry, as techniques for avoiding horse flies are now known.