Plains Zebra (Equus burchelli) (WC)

It’s a question that has puzzled me since childhood, I know, I should have had more things to worry about! There are many different theories as to why Zebra have stripes. The three most common theories are firstly is that they act as markers allowing individual Zebra to recognise each other in large herds. On its own this theory doesn’t hold much water with me, however, as other herd animals, such as the Wildebeest, still recognise each other despite the fact they do not possess these fingerprint like stripe patterns.

The second theory is that the black stripes on a Zebra will absorb a lot of heat from the fierce African sunlight, whereas the white stripes will reflect a lot of heat. The result of this is the downward movement of air from the black stripes and an upward movement of air from the white stripes, this difference in air movement then creates many small whirling winds on the Zebra body. This movement of air is said to help cool the Zebra down.

The third, and perhaps most quoted theory, is that the stripes help the Zebra to evade predators. The stripes help to camouflage the animals as the stripes break up the body against its background, in herds the action of running together also causes confusion to predators, such as the Lion, as they cannot distinguish between individual animals easily.

New research has now discovered another factor that may have influenced the stripes of the Zebras coat. The new study suggests that the stripe pattern scrambles the vision of a much smaller predator, namely the bloodsucking Horsefly. Horseflies, the females of which feed on blood, are attracted to light waves that are oriented in a particular direction, which we experience as glare. This glare lures these vampire bugs, it is theorised, because it resembles light reflected off water, where they lay their eggs. The black and white pattern is thought to help to disrupt the signal of light waves to the Horseflies, acting as a kind of natural fly repellant!

When I read this study I wondered why other Equine species were not striped in a similar fashion, but then I remember reading a book about horse breeds, I know I need a life, and remembering that some ancient horse breeds, as well as horse species in cave paintings sometimes exhibit faint stripes on their legs, although not as distinct as the Zebra’s. The Przewalski Horse also exhibits some striping on the leg. The fact there are more Horseflies, and more Horsefly species in Africa in comparison to more temperate areas maybe a reason why the striping is reduced or absent, not to mention the intense selective breeding of modern horse breeds. Although why other African species have not adopted this strategy remains a mystery.

Perhaps we will never know exactly why a Zebra has stripes, although if I had to put my life on it I’d say it’s probably a combination of all these factors and probably a dozen we clever humans haven’t even thought of yet, although not knowing doesn’t subtract, for me, the astonishing spectacular these unusual animals make in the African savannah.

2 Comments

  1. Thanks! :) This will help me loads with my homework on Zebras, my favourite animals apart from Flamingoes!

  2. Very interesting! I think I’m going to go with theory number 2!

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