A team of researchers form the Calgary and UC Davies Universities discovered that the stripes of a zebra are not for camouflage, as it was believed in the past by many scientists.
The lead author of the study, Amanda Melin from the Calgary University, said that her team discovered that the zebras don’t use their stripes for camouflage or social purposes, as many theories say. The researchers calculated the distances from where the lions and the hyenas could spot the zebras, during daylight, moonless nights and twilight. Previous studies done by Tim Caro from the UC Davis University have shown that the purpose of the zebra’s stripes is to discourage the biting of the flies.
First of all, the researchers wanted to see if the purpose of the stripes was indeed the camouflage. They discovered that it wasn’t true, as when the predators are close enough to see the zebras, they have already smelled or heard them. The researchers rejected this hypothesis, that has been previously debated by Alfred Russell Wallace and Charles Darwin.
In order to prove that the hypothesis was not accurate, the researchers took pictures of zebras in Tanzania and then they changed the images in order to simulate how they are seen by their predators, which are mainly spotted hyenas and lions and how they are seen by other zebras as well. The light contrast and the widths of the stripes were also measured to see what exactly is the maximum distance from where the hyenas and lions can spot the stripes, according to data about their visual capacities.
The researchers discovered that the stripes of the zebras can be spotted from 164 feet during daylight, from 98 feet at twilight and from 29 feet during the moonless nights. Apparently, even though the stripes can be easily spotted by humans, the predators have some difficulties in spotting them. In the past, theories stated that the white stripes copied the shafts of lights and the black ones copied the tree trunks, providing the zebras good camouflage in the wooded areas. The researchers proved that the theory was wrong, and that in the open areas where the zebras spend most of their time, the predators can see them as easy as they can see other preys with colored hides like the topi and the waterbuck.
Another theory that has been proved wrong by the researchers is that the zebras don’t use their stripes in order to better recognize each other from the distance. Apparently, other species of animals that are close to the zebras still recognize their species, even though they have no stripes. The researches managed to prove not only that the stripes of a zebra are not for camouflage, but that they don’t help them in recognizing individuals from their species either.
Image Source: www.upload.wikimedia.org