Why zebras have stripes

10 February 2012

Scientists claim to have solved the mystery of why zebras have their characteristic black and white stripes. A study published in the Journal of Experimental Biology showed that the striped pattern made the animals much less attractive to insects.

Reporter
Victoria Gill

White stripes could have been a result of natural selection

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There have been many theories to explain the zebra's unmistakable stripes. Scientists have suggested that each zebra has a unique pattern that lets other animals recognise it. Or that the mass of black and white in a vast herd provides confusing camouflage that puts off predators.

But this team set out to test exactly what effect the stripes had on a zebra's most irritating and ubiquitous enemy - the blood-sucking horsefly.

As part of their experiment the team put sticky horse models - one white, one black and one zebra-striped - into a fly-infested field. When they collected the flies that had landed and stuck to each of the models, they found that the model zebra attracted by far the fewest flies.

The researchers think that zebras had a black-coated ancestor, which evolved its white stripes in an evolutionary arms race, with an insect that's become the biting, disease-carrying scourge of most horse herds.

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Vocabulary

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unmistakable

something you can't confuse with another thing

camouflage

clothing or pattern designed to prevent the wearer from being seen

predators

an animal that hunts

irritating

annoying

ubiquitous

found everywhere

horsefly

a large flying insect which bites horses and other animals

fly-infested

filled with flies

ancestor

a past relative of

evolved

developed gradually from

scourge

something that causes suffering