Why Zebras Have Black And White Stripes: New Study Says Not For Camouflage


Zebras are distinct because of their black and white striped coats. What's fascinating about these striped coats is that they come in different patterns that are unique to each zebra.

Scientists have thought that these animals' black and white stripes are helpful in camouflage, or in mate selection, as Charles Darwin argued.

However, a study conducted at the University of California, Davis found that these concepts may be inaccurate as we have been looking at zebra stripes the wrong way.

How Predators See Zebra Stripes

It has something to do with the way predators such as cheetahs and lions see zebra stripes in certain lighting conditions, researchers said.

For instance, during moonless nights, zebra stripes are only visible to predators at 29 feet. At twilight, the stripes are visible within 98 feet. In short distances, predators can distinguish zebras through their sense of smell and hearing. Thus, this renders camouflage as ineffective.

Additionally, in long distances, zebras themselves cannot tell the difference between solid and stripe patterns. Researchers said this indicates that their unique stripe coats don't serve as a social function either.

What Are Zebra Stripes For, Then?

It is important to note that camouflage involves blending in the environment. So this means that zebras don't really blend in to protect themselves from predators. Still, their black and white stripes are not without function.

1. Cooling Effect

According to a 2015 study issued in the journal Royal Society Open Science, the black and white stripes of zebras may have evolved to help these animals cool off under the heat of the midday sun.

Researchers at the University of California, Los Angeles examined how 29 different environments can influence the stripe styles of plains zebras in south to central Africa.

The team found that the stripes along the back of a zebra are closely linked with temperature and precipitation in the environment. This means that stripes in the animals' torso do more to help zebras regulate their body temperature than to camouflage themselves.

Biologist Brenda Larison, co-author of the study, said zebras benefit from the extra cooling system because they digest food less efficiently than other grazers.

These black and white striped animals need to spend more time out in the heat of the midday sun and eat more food.

"Zebra have a need to keep foraging throughout the day, which keeps them out in the open more of the time than other animals," said Larison. "An additional cooling mechanism could be very useful under these circumstances."

2. Fending Off insects

Another idea is that the black and white stripes help zebras fend off disease-carrying insects.

Biologist Tim Caro of the UC Davis and his colleagues support this theory.

In a 2014 study featured in the journal Nature Communications, Caro and his team found that striping patterns are linked to repelling insects.

"Again and again, there was greater striping on areas of the body in those parts of the world where there was more annoyance from biting flies," said Caro.

Referring to the study conducted by Larison's team, Caro said they found a lot of similarities in their findings.

"A lot of people in the public think that stripes have to do with confusing predators," he said. "This is the kiss of death for that particular idea."

Photo : Filip Lachowski | Flickr

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