Zebras are remarkable animals, a sweet look-alike mix between horse and donkey. Their black and white pajamas are highly recognizable, and make them stand out in the African savannah.
Did you know that every zebra has unique stripes?
Zebra stripes are like human fingerprints and no two are ever the same. But why do zebra have such unique stripes? And how do zebra get stripes when horses do not?
Even today we don’t have a definitive answer to these questions. This article discusses all the hypotheses and mysteries. So you can form your own opinion on the uniqueness of zebra stripes.
Quick Zebra Facts
Swahili Name: Punda milia.
Scientific Name: Equus burchelli (Plains/Burchell’s Zebra), Equus grevyi (Grevy’s Zebra) and Equus zebra (Mountain Zebra).
Shoulder Height: 1.3 m.
Mass: 227-325 kg.
Lifespan: 40+ years (in captivity).
Habitat: From woodlands to open plains.
Diet: Essentially grazers, though they may occasionally browse. Zebras also dig for rhizomes or roots.
Faeces: Elongated shape, similar to warthog droppings.
Gestation: 12-13 months.
How Do Zebra Get Their Stripes?
Encountering a zebra herd is one of Africa’s most iconic experiences. These magnificent mammals stand out from the grass, a mass of black and white stripes framed against the wilderness.
But underneath these black and white stripes, zebra look just like horses. They have a black tan skin. It is only their fur that is striped.
Zebra start with white fur. Special skin cells transfer the black pigmentation from their skin, therefore making stripes.
This is a similar process to other African mammals. Cheetah only have spots on their fur, but tigers (not from Africa) have striped skin. All giraffe have the same light tan, yet every giraffe species has different patterns on its coat.
You can observe this in foals. Young zebra do not have black and white stripes, but soft brown markings instead. Basically, the skin pigmentation only fully transfers when the zebra reaches 18-24 months.
Zebra split from horses 3 million years ago. The two species remain so similar that they can breed together. Skin pigmentation can explain how each zebra gets its stripes. But how did they evolve to have stripes in the first place?
A Story from the San of the Kalahari
We could go into a rich scientific explanation concerning evolution, including the theory that striped horses appeared more than once throughout mammal history.
However, the best explanation is a tale told around the campfire by the San bushmen of Namibia’s Kalahari. After all, scientists can claim all they want, but it is the San who have spent their lives living side by side with zebra.
A long long time ago, deep in the Kalahari, a boisterous baboon guarded the last remaining waterhole. He said he was the lord of the water and forbade every other animal from drinking.
A thirsty pure white zebra decided to fight the baboon so his herd could drink. With one mighty kick he sent the baboon flying onto the rocks. The baboon landed on his bum with such vigour it ripped the hair clean off. Baboons have had bald bums ever since!
The victorious zebra was too exhausted to think about his victory and fell backwards over the baboon’s fire. This scorched him with black burn stripes.
The shock of the burn sent him galloping onto the savannah where the zebra would stay forever. The baboon stayed high on the rocks and continued to be boisterous, but could only bark at strangers from up high.
Different Zebra Species and Their Stripes
Before considering different scientific theories it’s important to understand that not all zebra are the same. There are three different zebra species and each of these has unique stripe variations.
Plains zebra (also called “Burchell’s zebra”) are the most numerous. They live in huge numbers across East and Southern Africa, including more than 300,000 that take part in the great wildebeest migration through Serengeti National Park.
Mountain zebra are a vulnerable species living on the hot mountain rocks of Southern Africa. They are the smallest zebra species and have much narrower stripes.
Grevy’s zebra are one of the rarest sights on an African safari. Now confined to small areas of Tanzania and Kenya, these are the largest zebra and have the most tightly packed stripes. Their body shapes resembles a mule, rather than a horse.
Mountain and plains zebra have stripes all over their bodies. Grevy’s zebra lack stripes on their underbelly.
Why Do Zebra Have Their Stripes – The Theories
Five compelling theories have been put forward and each does have more scientific street cred than the San tale. Still, none of these theories have been conclusively proven.
Ultimately, we still do not know why. So make up your own mind.
One of the first theories was that unique stripes help to keep a zebra cool.
Black and white absorb sunlight differently. When air hits the black stripes it flows faster, because black absorbs heat. Then the air slows down when it reaches the white stripes.
This creates air currents. When these currents collide they form swirls of air, just like a fan. So the stripes are a form of thermoregulation.
A favourite proverb says that a leopard cannot change its spots. Well, zebra may be able to change their stripes. Studies have shown that plains zebra have wider and more spaced out stripes the further south in Africa they are found.
The argument is that the tighter the stripes the greater the need to cool down and the faster the natural fans. It is true that zebra living around the equator have the closest stripes. But what about mountain zebra living in the Cape with jam-packed stripes?
Some researchers have discredited this thermoregulation theory. Instead of studying wild zebra, they wrapped zebra skins around oil barrels and studied the temperatures over four months.
Their conclusion was that stripes didn’t change the temperature in the barrel, so zebra don’t need stripes for thermoregulation. How is that considered science? Better listen to the San instead! 😉
To avoid tsetse flies
Author Tim Caro wrote a whole book on zebra stripes. It painstakingly, and rather boringly, goes through all the evidence, before concluding that zebra stripes are a natural defence against biting tsetse flies.
Observations show that striping is most intense in areas where biting flies are most abundant. The theory is that tsetse flies want to land on a hide that is a single colour, such as a wildebeest or buffalo.
Black and white stripes confuse the tsetse fly and camouflage the zebra. So the unique stripes are not a defence against lions, but against the diseases brought by biting flies.
2019 research argues that when flies get close to a zebra they either fly over the stripes, or crash-land.
But zebra also live in areas where there is no evidence of tsetse flies. If stripes are all that is needed, why don’t other animals such as wildebeest have them? And why do all zebra need unique stripes?
Social interaction and identification
One thing that zebra do not have in common is their stripes. Every single zebra in the world has its own pattern.
This basic fact gives rise to another hypothesis: zebra stripes are a means of identification. Not much explanation is needed. One zebra can look at a herd and find its friends through visual identification.
Others have proposed that these unique stripes are also used for social purposes. Nobody is sure how this could work. Maybe herds are made up of zebra with similar stripes? Or could the stripes be a means of impressing a mate?
Disruptive coloration to avoid predators
The classic hypothesis is that stripes are a form of camouflage. It was first put forward by Charles Darwin, somebody who knew a lot about animal evolution.
A 2016 study in the PLOS ONE journal discredits this theory, arguing that “by the time predators are close enough to register the stripes – and be tricked by them – they will have caught the zebra’s scent.”
However, the purpose of unique stripes is not classic camouflage. Instead, Darwin said that the stripes prevent predators from identifying an individual. They can see and smell the herds, but struggle to catch one.
Zebra typically huddle together in close-knit herds. This contrasts wildebeest herds, which are spread out over large distances.
Black and white is not a good camouflage for green grass. However, when the herd moves it causes something called motion blur. The black and white stripes coalesce into a single mass, making it difficult for predators to locate a target.
The patterns confuse and obscure. The stripes blend and overlap and flicker. It could be so confusing that a predator doesn’t even know which way the zebra herd is running.
Anyone who has been on an African safari, especially in the Serengeti, can concur with this theory. When viewed from a distance, a herd of zebra appears to be a single mass of grey.
So how about Darwin’s theory?
Zebra stripes are invisible at night
Big cats mostly hunt at night. So do predators see unique stripes at night? The answer could be unexpected. According to one researcher, zebra turn invisible at night.
When tracking wildebeest in the Serengeti, Dr Anthony Sinclair claims that wildebeest would suddenly disappear.
He could see wildebeest as black shapes against the pale grass. However, zebra were the exact same intensity of light as the background, as Sinclair explains in this video. The disappearing wildebeest were caused by zebra crossing their path.
Big cats have incredible eyesight so maybe the stripes are a means of re-balancing this disadvantage? Could they be a means of camouflage after dark?
Why are Zebra Stripes So Unique?
All these hypotheses have their pros and cons. There really is no definitive explanation. But there is another question that is yet to be even fully considered.
Why does every zebra have unique stripes? Why don’t all zebra have the same pattern of stripes?
Studies have proven how zebra stripes have evolved differently dependent on where they live. But why?
The answer could be a combination of all the theories above. Unique stripes can certainly help identification. They could make an animal cooler. A variation in stripes would help create a more hazy motion blur.
Scientists may say that skin pigmentation occurs differently in every animal, so leopard have unique spots and zebra unique stripes.
There are so many mysteries in the world of African wildlife. Rather than try to understand the uniqueness of zebra stripes, let us simply admire these incredible animals and their beauty.
People can argue about whether zebra stripes confuse predators. What we know for certain, is that zebra stripes continue to confuse us. 🙂