Originally Posted by aico

Black, but that's not advice, but now I'll drop some knowledge:

During vertebrate development, a group of cells called neural crest cells gives rise to the brain and migrates down the axis of the animal to develop into the spinal cord. Some of these neural crest cells along the spinal cord differentiate into melanocytes, or cells that produce colored pigment. These melanocytes then migrate perpendicular to the spinal cord, developing into pigmented skin. The exact pattern of pigment in different animals depends on the genetic regulation of melanocyte differentiation and migration.

Among the three species, the common (or plains) zebra has 26 stripes per side, the mountain zebra has 43 stripes per side, and the Grevy's zebra has 80 stripes per side. To account for these patterns, Jonathan Bard of the University of Edinburgh has proposed that the original pattern of melanocyte differentiation is the same in all three species, but the differentiation occurs at different times in development.