Why are zebra stripy?

It might not be as simple as camouflage

A zebra’s black and white stripes are its most recognisable feature. Stripes of white hair follicles begin to appear on the black skin of a developing foal, so by the time it’s born it already has its patterned coat. For a long time, camouflage was the accepted reason for the evolution of the zebra’s stripes, but there are actually other theories about their origins:

 

Insect repellent

Since the 1930s, it’s been proposed that flies don’t like stripes and prefer to land on patches of solid colour. Scientists aren’t completely sure why this is, but think the flies could find striped surfaces hard to recognise. There seem to be more striped animal species in hot parts of the world with high densities of insects, so the zebra’s coat could stop them from constantly being bothered and bitten.

 

Predator confusion

Black and white stripes are unlikely to help static zebra blend in against the plain browns of the open savannah, but they could confuse predators and give an animal under attack a few extra seconds to get away. When zebra run and turn, especially moving in a herd, some people believe the movement and stripes combined make it hard for hunters like lions to focus on a target and accurately judge its position – an effect called motion dazzle.

 

Temperature regulation

In 2015, scientists observed that zebra in hotter areas have more stripes than those in cooler climates. Zebra are less effective at digesting their food than other African herbivores, so they have to spend longer grazing to make sure they get enough energy; with these extra hours under the hot sun, an additional method of keeping cool would be very useful. It’s been suggested that air moves faster over the black hair than the white and that tiny breezes are created where the stripes meet, but this is disputed.

 

Each of these theories is supported by some animal experts and disputed by others. All three could have played a part in the evolution of the stripes, or just one. The solution could, of course, be something that hasn’t even been thought of yet. A zebra’s coat is so familiar and recognisable, but it looks like it could remain a mystery to us for a while longer.

 

Image: Megan Coughlin/flickr