When you walk through a park, go for a hike or take a trip to the zoo, most of the animals and plants you see appear symmetric. Whether it’s an oak leaf or an elk’s antlers, the right and left sides match. It’s much less common to find examples of asymmetry -- or things that are out of balance -- in nature.
But scientists aren’t exactly sure why symmetry is so prevalent. One idea is that it may be beneficial to have a spare body part in case one side is injured. Or perhaps it’s just easier to move through the environment with matched pairs of legs, fins or wings.
Symmetry also tends to look balanced and harmonious to our eye. And we’re not alone in that feeling.
Many animals seem to show a preference for symmetry in a potential mate. It can be a clue that the mate has the genes necessary to develop properly and thrive in an environment full of stresses and dangers.
But some critters buck the trend. Like the earwig, a diminutive insect found on every continent except Antarctica.