Why zebras have stripes?

Pourquoi les zèbres ont-ils des rayures?

The zebra’s stripes are posing big questions on their usefulness to biologists for a long time. Several studies in recent years provide an answer to this bizarre animal.

But what can serve the stripes of the zebras? This peculiarity of the only horses with stripes has intrigued scientists for several generations. Several hypotheses have been made: – to facilitate the camouflage in the tall grasses of the savannah, confuse predators with the sight low, reduce the heat of the african sun…

It is not the case. This is to avoid the insects. A british scientist, Tim Caro, has spent most of his time in recent years, to investigate the matter. In a study published in April 2014 by the scientific journal Nature Communications, he explained that the striped dress of the zebra using to combat insects and other parasites that swarm close to the large herds that travelled through the african savanna. Indeed, it would seem that the surfaces are struck are less attractive to mosquitoes, flies and other horse flies, who prefer the plain surfaces.

In another article published in February 2019 in the journal Plos One, Tim Caro has explained this phenomenon, and why zebras are less than the target tsetse flies and horseflies. From afar, the stripes are not used for nothing: the zebras, as the other horses, attract insects by their scent. But up close, everything changes: arriving on horses, insects slow down for landing, so that they don’t do it for the zebras. The stripes offer an optical illusion, an assumption confirmed by experience of the teams of Tim Caro who have dressed horses with tunics to zebra: as for the zebras, horses and disguised were less attacked by flies and horseflies, which could not see the landing areas.

In 2012, the british researchers explained in the Journal of Experimental Biology that they had deposited in a field riding several tables coated with glue to insects: a white, a black, and many with stripes of different sizes, and then they counted the number of horseflies collected by each table. The results showed that the table with the design resembling the most to that of the zebra, was the one who collected the least amount of insects.

It should be noted that all zebras have stripes different this allows, in the manner of a bar code, scientists to differentiate individuals between them.

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