Countershading

Countershading is a form of camouflage in which an animal’s dorsal surface is darker than its ventral surface. This gradient reduces the contrast created by directional lighting, helping the animal blend with its background when viewed from above or below. The effect can make the body appear flatter and less three-dimensional, hindering detection by predators or prey.

In nature, countershading is widespread across oceans and land and is common in many species: sharks and most pelagic fish have dark backs and pale bellies; penguins and many seabirds show a similar pattern; terrestrial mammals such as gazelles or deer often have darker upper parts and lighter undersides. It works best under natural lighting, where sunlight comes from above and the sky provides a lighter backdrop on the belly side.

The concept originated with Abbott Thayer (1849–1921), who popularized the idea in Concealing-Coloration in the Animal Kingdom (1909). The term countershading and its broader understanding were later developed by zoologists such as Hugh Cott in Adaptive Coloration in Animals (1940). Since then, countershading has been recognized as one of the most common camouflage strategies in nature, often combined with other forms such as disruptive coloration.

Outside biology, countershading has influenced human camouflage design, including military uniforms and equipment intended to reduce visibility in daylight. It also appears in various forms of art and fashion that seek to minimize visual impact under specific lighting conditions.