Truth or Fiction?
Do the stripes of a zebra actually help it stay cool under the searing African sun?
Zebras may have the coolest pelts on the savannah, but that doesn’t stop them overheating, according to new research. Their stripes are as mysterious as they are striking; about 18 different hypotheses have been put forward over the years to explain their function – ranging from camouflage to communication to optical illusions that deter biting flies or cause carnivores to mis-time their lunges.
Now, however, biologists from Sweden and Hungary have narrowed things down, if only slightly, by ruling out another possibility – that stripes help keep zebras cool in the sun.
The theory goes that the black stripes heat up more than the white ones, thus creating little swirling vortices in the air above them, which keep air moving across the fur resulting in a net cooling effect.
To test whether this works in practice, biologists filled zebra-sized barrels with water, covered them with zebra, cow and horse hides of different shades and left them out in the sun. Unsurprisingly, the water temperature rose highest under black pelts and remained cooler under white ones. Crucially, though, the black-and-white stripes did not keep the water any cooler than did uniform grey pelts. SB
The evolutionary purpose of the zebra’s distinctive coat remains elusive.