Have you ever wondered why zebras have their interesting and unique black and white markings? I have, but never went out of my way to research it.
I found an interesting article on Nation Geographic about why zebras evolved to have their black and white stripes, so I decided to find answers about their coloration and provide you guys with answers too, just in case you were too lazy to figure it out on your own.
History says that a zebras black and white stripes camouflage the animal in tall grass- the better to evade the colorblind lion. But a new study says the pattern was actually made to scramble the vision of a tinier predator…the horsefly.
The female horseflies feed on blood and are attracted to polarized light (light waves that are oriented in a particular direction which we can related to as glare). The glare attracts the bug most likely because the light reflects off water where they lay their eggs.
On horses, black fur reflects polarized light better than brown or white, as evolutionary ecologist found in a pervious study.
So zebras, having a mixture of colors in their coats, would be less attractive to flies than those of black horses but more than those of white horses.
But after experiments in which the team measures the numbers of horseflies that because trapped on gluey strip boards of model horses, they found that zebra stripes are the BEST fly repellant! And even the narrower the striped the better.
This may explain why zebra’s skinniest stripes are on their faces and legs to help them avoid the annoying horseflies.
So they continued to do research weather striped skin was more effective than white (which has the lowest reflectivity to polarized light).
They learned that the black and white pattern turns out to be ideal in its function of disrupting this signal of reflected polarized light. Because of the confusion between polarized and non polarized light its more difficult to single out relative to the surrounding.
So the unique stripes of zebras are not only useful for camouflage from big cats but also annoying flies.
So you are probably wondering if zebras could evolve these useful stripes why cant horses?
Akesson who performed the experiments above believes that it is because there are more horsefly species in Africa compared to more temperate regions where horses live. Zebras were under more pressure to evolve a deterrent!
Also modern horses may have their natural big repellant bred out of them my humans. She says, “We have maybe created coat patterns that we like but maybe no what would have been favored by nature.”
Because horses are in so much contact with humans, and have the help of humans against those annoying flies they have not had a reason to evolve a deterrent like the zebras in the wild of Africa.