Egg Shapes Explained

FRANS LANTING/FRANS LANTING STOCK/NATIONAL GEOGRAPHIC CREATIVE

AMAZING EGGS! Bird eggs come in a spectacular variety of colors, shapes, and sizes, depending on the species.

Why do bird eggs come in so many different shapes? To find out, a team of scientists analyzed nearly 50,000 eggs from 1,400 species. They looked at each egg’s symmetry (how similar the two ends are) and ellipticity (how oval an object is). They discovered that the strongest fliers lay the pointiest and most elongated eggs. Compared with birds that don’t fly much, like chickens and domesticated ducks, the bodies of fast or long-distance fliers are narrower and more streamlined. “That makes it difficult to lay a round egg,” says Mary Stoddard, a biologist at Princeton University in New Jersey who led the study.

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