As animals grow, their bodies usually change in size and shape. For some, their shape changes very little. For young amphibians, fish, and insects, the change is more dramatic and the young look very different from the adults. This process of change is called metamorphosis.

Insects may change in two ways. If they go through complete metamorphosis, their shape changes suddenly and the adults look very different from the larva. If they go through incomplete metamorphosis, their shape changes more gradually and the adult resembles the larva, only bigger.

In this video, Ted and Barkley are talking about complete metamorphosis seen when caterpillars become butterflies. The adult female lays an egg. This egg will hatch into the larva. The caterpillar is the larva stage and is an eating machine – its mission is to eat and grow. Once it grows to a certain point it will attach itself to something, and become a pupa, the next stage to complete metamorphosis. This is a time of rest and internal change. For a butterfly, the pupa stage is called the chrysalis. The chrysalis looks like a pod or shell. Once the pupa has changed, it breaks out of its shell and emerges as an adult, or butterfly.

Butterflies are not the only insects to go through complete metamorphosis. Beetles, moths, flies, wasps, bees, and fleas also have four stages to their development. Growth and development in frogs is also complete metamorphosis.

Bugs, damselflies, and grasshoppers change through incomplete metamorphosis. The eggs hatch into nymphs. Nymphs look very much like the adults, just without wings. They live in similar places to the adults. Gradually, the nymphs will grow and shed their skin. With each shedding, the nymph becomes more and more like the adult.