Scientists Say: Metamorphosis

Metamorphosis is a drastic transformation in an animal’s appearance from youth to adulthood 

two orange and black butterflies perch atop yellow flowers

Monarch butterflies (pictured) and many other insects undergo a transformation called metamorphosis as they grow up.

Steve Satushek/Getty Images

Metamorphosis (noun, “Met-uh-MOR-foh-sis”)

Metamorphosis is a drastic change in an animal’s appearance as it grows up. All animals change somewhat as they get older. In some species — such as humans, dogs or cats — young animals look like mini versions of their parents. Animals that go through metamorphosis experience much bigger changes. They might lose tails or grow legs or wings. 

a yellow and black striped caterpillar sits atop a plant stem
This monarch caterpillar will undergo metamorphosis, transforming into a monarch butterfly like the one seen at the top of this page!Jasius/Getty Images

This process is especially common in insects. Perhaps the most famous example is a butterfly. When a butterfly egg hatches, a caterpillar emerges. That caterpillar later becomes enclosed in a chrysalis. There, it grows wings and other adult body parts, emerging as a butterfly. This total overhaul of the insect’s body is known as “complete metamorphosis.” Other insects go through “incomplete metamorphosis.” That process involves changes that are less radical. Crickets, for instance, are born without wings. But for the most part, young crickets look mostly like small versions of adult crickets.

Many amphibians go through metamorphosis, too. Frogs hatch as tadpoles. Those little swimmers later lose their tails and grow legs to hop around on land. Their gills also disappear and their lungs take over for breathing. Metamorphosis is also seen in sea dwellers such as sea stars, crabs and clams. 

In a sentence

When amphibians called hellbenders go through metamorphosis, they grow lungs.

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Maria Temming is the assistant editor at Science News Explores. She has bachelor's degrees in physics and English, and a master's in science writing.

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