When a caterpillar hatches out of its egg and begins to eat leaves, it has certain characteristics in common with all other caterpillars. Its body is made up of many segments, each with a pair of legs, so it also has many legs.

Its mouth is designed to chew on leaves, its eyes are simple, and it does not have antennae on its head.

It has a soft body, covered with a flexible skin, and it must crawl in order to get around. The caterpillar placidly munches its way through its growth phase, crawling around from one leaf to another. Then one day, an internal timing mechanism goes off, orchestrated by its glands and hormones, and the caterpillar spins a chrysalis around itself until it is completely enclosed. The chrysalis hardens and then a most miraculous transformation occurs.