Baby zebras are born with stripes. These distinctive patterns are present from the moment a foal enters the world, though their initial appearance differs from that of adult zebras. The formation and purpose of these unique patterns have long intrigued many scientists.
Newborn Zebra Stripe Characteristics
A newborn zebra, known as a foal, emerges with stripes that are brown and white, rather than the stark black and white seen in mature zebras. These brownish stripes gradually darken, transitioning to black between 9 and 18 months of age. Each zebra possesses a unique stripe pattern, much like human fingerprints, established at birth. This individual uniqueness allows mares and their foals to recognize one another within a herd, assisting in social bonding and identification.
How Zebra Stripes Form
Zebra stripe formation is a complex biological process beginning early in embryonic development. While the visible pattern appears around the eighth month of gestation, its underlying blueprint is determined much earlier. Specialized cells called melanocytes produce melanin, the pigment giving skin and hair its color. In zebras, “black” stripes contain active melanocytes producing pigment, while “white” stripes are areas where these cells are inactive or absent.
Scientists attribute stripe formation to a reaction-diffusion process during development. This involves two chemical substances, an activator and an inhibitor, creating periodic patterns across the developing skin. These chemical signals influence melanocyte activity and distribution, resulting in the distinct striped arrangement. The skin underneath a zebra’s fur is uniformly dark, indicating stripes are formed by pigment presence or absence in hair follicles, not skin color variations.
Why Zebras Have Stripes
The purpose of zebra stripes has been a subject of scientific inquiry, with several theories proposed. One leading hypothesis suggests stripes primarily deter biting insects like tsetse flies and horseflies. Studies indicate the striped pattern confuses insect visual systems, making it difficult for them to land. This protection from insect bites is very important, as these flies can transmit diseases.
Another theory posits that stripes aid in thermoregulation. The alternating black and white stripes absorb and reflect sunlight differently, creating small temperature variations across the zebra’s coat. This temperature gradient may generate tiny convection currents that help cool the animal by enhancing sweat evaporation.
Additionally, stripes may contribute to a form of camouflage known as disruptive coloration, which can break up a zebra’s outline and make it harder for predators to single out an individual within a moving herd. However, recent evidence suggests this camouflage effect might be less significant than previously thought, especially given that major predators like lions are colorblind.