Aerial view from a helicopter of a group of Burchell Plains Zebras (Equus quagga burchellii), Okavango Delta, Botswana. Source – Diego Deiso. CC SA 4.0.
Zebras are iconic for their distinctive black and white stripes, but have you ever wondered if zebras are white with black stripes or black with white stripes?
Zebras are African equines of the genus Equus (like horses) and belong to the subspecies Hippotigris. There are three living species, the Grévy’s zebra (Equus grevyi), plains zebra (E. quagga), and the mountain zebra (E. zebra).
While the stripes on each zebra are unique to each individual, the three species each have a different stripe pattern. And if that isn’t enough to confuse you, for some zebras the darker parts of their skin are black, while others have a more brown coloration, and some have stripes only on the body but not on the legs. .
It should be mentioned that there was a fourth species of zebra called the quagga (E. quagga quagga). This zebra was endemic to South Africa until it was hunted to extinction at the end of the 19th century by European colonists.
It was long thought to be a separate species, but early genetic studies have supported it to be a subspecies of the plains zebra. He had minimal scratches on his head, mane and neck, according to The Quagga project.
But we still need an answer to the question
Despite all the differences in the stripe patterns, all zebras have the same skin color: black, said Tim Caro, behavioral and evolutionary ecologist and conservation biologist at the University of California at Davis.
Even still, we have to look at the zebra’s melanocytes, or the cells that produce the pigment in their fur, to decide if a zebra is white with black stripes or vice versa. And there are also the variations that we see genetically.
So while zebras have black skin, different developmental processes determine the color of their fur, just like a light-skinned person can have dark hair, Caro said. He adds that zebras actually have more light hair than dark hair, especially on their stomachs.
This might lead us to believe that zebras are white with black stripes, right? But that’s not the case, according to a 2005 review in the Journal of Investigative Dermatology.
Each hair of a zebra, whether light or dark, grows from a follicle filled with melanocyte cells. These cells produce a pigment called melanin which determines the color of hair and skin.
So a lot of melanin leads to darker colors, like dark brown or black, while less melanin leads to lighter colors, like hazelnut or blond, Previously reported live science.
The black fur of zebras is full of melanin, but the melanin is absent from the white fur, essentially, because the follicles that make up the stripes of white hair have “turned off” the melanocytes, which means that they do not produce. pigment.
OK, are you ready for the answer? Melanin production “stops during the development of white hair, but not black hair,” Caro said. Science live in an email.
That is, for zebras, the default state of animals is to produce black hairs, making them black with white stripes, according to Brittanica.
A study published in 2020 in the journal Proceedings of the Royal Society B, found that African horseflies alighted less frequently on horses wearing striped or checkered blankets than on horses wearing plain blankets. These biting flies can carry deadly diseases to zebras.
“There are indeed very few mammals with contrasting stripes like a zebra,” Caro said. “The okapi has similar stripes on the rump, but other than that, no other species has really distinct black and white stripes. I guess the fly deterrent function is unique to equines because they are so susceptible to diseases carried by some biting flies in Africa.