Why do zebras have stripes?

How do we know?

↻ One of the pages with a moving picture

Scientists put coats on horses.

1. Old ideas: stripes might hide zebras from lions, keep them cool or help them know each other.
2. Scientists compared where striped animals live. The best match was places with lots of biting flies.
3. Horse flies circled zebras and horses equally, but failed to slow down near zebras. So far fewer landed!
4. Scientists think the stripes may dazzle a fly’s eyes just before it lands. They’re still testing why!

Scientists put cloth coats on horses: black, white or striped. Fewer flies landed when the horses wore stripes.

They also filmed horse flies around zebras and horses on a farm in North Somerset, England.

Zebras once lived much farther north. About 6,000 years ago, Grévy’s zebras roamed as far north as Egypt. Today they live in only a small part of Africa.

Wow number

6,000 years ago, Grévy’s zebras roamed as far north as Egypt. Today they live in only a small part of Africa.

Myth or fact?

A zebra’s stripes go all the way around its belly. Myth. Most zebras’ stripes stop at the belly.

Grévy’s zebra is the largest kind of zebra. Fact. It has bigger ears than other zebras, too.

Think about it

If you were a scientist, how would you test the biting-fly idea?

Where in the world?

Northern Kenya where most of the world’s Grévy’s zebras live. They are the biggest zebras, with big ears. Scientists filmed horse flies around zebras and horses on a farm in North Somerset, England — 0.5833° N, 37.5333° E.

Where these facts come from

Every number on page 51, and who measured it

Has this changed?

Yes, this one may change. Scientists are still testing exactly why stripes keep flies away.

Other ideas, like hiding from lions or keeping cool, did not match the evidence as well as the flies did.

Words from this page

horse fly

A big biting fly that bothers horses and zebras.

Grévy’s zebra

The largest kind of zebra, with big ears. Most live in northern Kenya.

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