Why do zebras have stripes?

Zebras have stripes mainly because the pattern helps keep biting flies from landing well. The black-and-white bands disturb the light signals those insects use when they approach skin, so many flies veer off, bump awkwardly, or fail to settle.

That matters because some flies spread serious disease, not just itchy bites. Over many generations, zebras with stronger striping were probably bitten less often and stayed healthier. Natural selection kept favoring coats that worked like fly confusion painted across the body.