A new study suggests that zebras’ black and white stripes function to help the animals to control their temperature. The research also points to a new a mechanism for how this control of body temperature might be achieved. With zebras, the stripes come in different patterns, unique to each individual.
For the study, British researchers assessed the temperatures of black and white stripes on two zebras and a zebra hide, with the readings taken on different days in Kenya. The analysis found a 12–15 degrees Celsius variation between living zebras’ stripe temperatures across a period embracing middle seven daytime hours.
As with any equid, zebras will sweat in order to keep cool. Recent research has shown how the movement of sweat away from the skin is assisted by a surfactant equid protein called latherin (which is also found in racehorses). The protein functions to lower the surface tension of the sweat, leading to rapid cooling at the hair tips.
The new research indicates there is a considerable temperature difference between the stripes of the zebra. This leads to varying air movement above the hair surface, which appears to enhancing evaporative heat dissipation and thereby leading to a more effective cooling system that seen with a horse. There is a difference in the orientation of black and white stripes which could also assist the cooling mechanism.
According to one of the researchers, Alison Cobb: “Ever since I read ‘How the Leopard Got His Spots’ in Kipling’s Just So Stories at bedtime when I was about four, I have wondered what zebra stripes are for. In the many years we spent living in Africa, we were always struck by how much time zebras spent grazing in the blazing heat of the day and felt the stripes might be helping them to control their temperature in some way.”
In contrast to other theories about why zebras have stripes, such as the stripes helping to deter biting flies, the researchers find that the main function of the stripes is with thermoregulation.
The research is published in the Journal of Natural History, with the study paper titled “Do zebra stripes influence thermoregulation?”