How does a caterpillar turn into a butterfly?

A caterpillar becomes a butterfly by sealing itself inside a chrysalis, breaking many of its tissues down, and using stored instructions in its cells to build a new body. The same animal stays alive, but its shape, mouth, legs, eyes, and wings are rebuilt for flying and sipping nectar.

The clever part is that tiny cell groups were waiting long before the chrysalis formed. Each group helps make one future piece, such as an antenna, a wing, or an eye. When the butterfly comes out, its soft wings must fill, stretch, and dry before the first flight.