Countershading

Countershading is a type of coloration commonly found in animals and means that the animal's back (dorsal side) is dark while its underside (ventral side) is light. This shading helps an animal blend in with its surroundings.

Description

In the ocean, countershading camouflages an animal from predators or prey. When viewed from below, an animal's lighter belly would blend in with the lighter sky above. When viewed from above, its darker back would blend in with the ocean bottom underneath.

Countershading in the Military

Countershading has also had military applications. German and U.S. military planes used countershading to hide from their enemies by painting the bottom of the plane white and the top of the plane to match the color of the surrounding area. 

Reverse Countershading

There's also reverse countershading, light on top and dark on the underside, which can be seen in skunks and honey badgers. Reverse countershading is typically seen in animals with strong natural defenses. 

Alternate Spellings: Counter Shading, Counter-Shading

Several rorqual whales are counter-shaded, including fin whales, humpback whales, and minke whales.