Tip for Reading List: Why do Zebras Have Stripes?


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 can not land on the equine. To reach this conclusion, the researchers conducted an unusual experiment involving zebras and horses dressed in black and white striped coats. When researchers painted a mannequin with zebra-like patterns, similar to those that adorn the skin of some tribal communities, they found that there were ten times fewer horsefly bites than on unstriped models. They say this offers evidence that zebra stripes provide protection from blood-sucking insects that spread diseases.

Dr Martin How, a member of the team from the University of Bristol, said: 'Stripes may dazzle the flies in some way once they are close enough to see them with their low-resolution eyes'.

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".

The experiment involved three zebras and nine horses with uniformly white, black, grey or brown coats. Today, many scientists believe that the black-and-white stripes actually function as a fly repellant, but because it's hard to get close to wild zebras, it hasn't been clear how the pattern might deter the pesky critters from landing on the animals and taking a bite. However, video analysis revealed differences in approach speed. The flies tended to fly over or glance off the zebras; when it came to horses, many more flies were able to stick the landing.

As a result, the exact cause of stripes in zebra remain unknown. Some researchers have said the stripes serves as camouflage to confuse big predators, an identity signal to other zebras, or even a kind of wearable air conditioner, according to the Times.

As additional protection, zebras swish their tails nearly continuously to keep flies off, the study found.

The bugs were still attracted to the zebras, and still pursued them from a distance, but couldn't nail the landing when they got close. A possible explanation is zebras may be highly prone to infectious diseases carried by African biting flies, although that hypothesis requires further study.

It's important to note that zebras also behave differently from horses in the presence of flies. The striped animals nearly continuously swish their tails during the day and will stop feeding if they feel bothered.