Why do zebras have their distinctive stripes? No seriously...why would evolution endow zebras with such an obvious pattern that provides next to no camouflage in the African savannahs? The question puzzled even our most celebrated biologist, Charles Darwin, who commented, “The zebra is conspicuously striped, and stripes on the open plains of South Africa cannot afford any protection.”
Even to modern day biologists, the question has been perplexing. Perhaps the stripes are a way the females choose their mate? Possibly – many male members of the animal kingdom have bizarre decorations such as brightly coloured plumage or heavy, unwieldy horns that are a clear disadvantage in survival but serve to attract the opposite sex – but that wouldn’t explain why the female zebras also have stripes.
Some animals use patterns and bright colours to act as warnings or camouflage– Researchers have found that when zebra herds move together, their stripes act as a large optical illusion. Any potential predator is momentarily confused, giving the zebras vital seconds to escape their clutches.
However, a group of scientists from Eötvös University in Hungary have found another solution, which is far less glamorous. It seems that the zebra’s intricate barcode pattern acts as one large insect repellent – in particular against horseflies. They found that horseflies are quite particular about where they land to prey. The narrow stripes on the zebra act to break up the hide and alter how the light is reflected off of it. These two factors make the zebra less appealing to the horsefly.
It seems remarkable how evolution can be defined by even the smallest of creatures and how a large creature’s body image can be influenced by a fly no larger than a thimble.
Posted on Thursday, 15th March, 2012