Zebras are animals that we differentiate since childhood by their striking appearance and color combination, but growing up, at some point we wonder if they are white with black stripes or black with white stripes.
The black and white coloration of the zebra’s skin is impressive, and its marked contrast stands out between the landscapes in which it is found: dry, brown and green grasslands without trees and the savanna forests of the east and south of Africa.
First of all, stripes are unique to each zebra and each of its species also has a different stripe pattern. As reported Live Science, there are three species of zebras today: the plains zebra (Equus quagga), the mountain zebra (Equus zebra) and Grevy’s zebra (Equus grevyi).
In some zebras the darkest parts of their skin are black, some have a more brown color and there are others that have stripes only on the body, but not on the legs. On the other hand, according to The Quagga Project, an extinct subspecies of the plains zebra called quagga (Equus quagga quagga) had minimal stripes on the head, mane, and neck.
Now, despite the different patterns and colors, according to Tim Caro, an evolutionary and behavioral ecologist and conservation biologist at the University of California at Davis. all zebras have the same skin color: black.
However, this data does not exactly answer the question of whether its coat is black with white stripes or vice versa. For that, as reported Live ScienceTake a look at zebra melanocytes, the cells that produce pigment for their fur.
According to Caro, although zebras have black skin, there are different developmental processes that determine their coat color, in the same way that a light-skinned person can have dark hair.
Zebras actually have more light-colored hair than dark hair; in fact, their bellies are usually light, which is why zebras may appear to be white with black stripes. However, this is not the case.
According to a 2005 review in the Journal of Investigative DermatologyEach strand of hair, both light and dark, grows from a follicle filled with melanocyte cells. And these cells produce a pigment that determines the color of hair and skin, which is known as melanin.
Too much melanin produces darker colors, such as dark brown or black, while less melanin produces lighter colors, such as brown or blonde.
In the case of zebras, their black fur is full of melanin, but in their white fur, melamine is absent. This is because the follicles that form the fringes of white hair have “dull” melanocytes, which means that they do not produce pigment. According to Caro, the production of melanin by melanocytes “is prevented during the development of white hair, but not in that of black hair.”
As the Encyclopedia Britannica, the default state of zebras is to produce black hair, so zebras are black with white stripes.
The exact biological processes behind zebra stripes are unknown, but it is probably related to what happens in the case of African striped mice (Rhabdomys pumilio).
According to a 2016 study in the journal NatureIn African striped mice, which have light and dark stripes along their furry bodies, the Alx3 gene is more active in light stripes than dark ones. This gene effectively stops a master regulatory gene in charge of melanocyte development, resulting in light-colored hair.
But even with that discovery, the zebra’s process to develop its stripes is still a mystery.
Still, according to Caro, the unique pattern of zebras can keep biting flies away. In a study published in 2020 in the journal Proceedings of the Royal Society B, African horseflies were found to land less frequently on horses that used striped or plaid carpets, compared to horses that used solid-colored carpets. These biting flies can transmit diseases that are fatal to zebras.
“In fact, there are very few mammals with contrasting stripes like a zebra,” says the ecologist, such as the okapi, a mammal of the giraffe family found in the jungles of the north of the Democratic Republic of the Congo.
The okapi “has similar rump stripes, but other than that, no other species has really distinct black and white stripes. I suppose that the fly deterrent function is unique to equidae because they are very susceptible to diseases transmitted by certain fly bites in Africa, ”concluded Caro.