In biology, any striking developmental change of an animal's form or structure, accompanied by physiological, biochemical, and behavioral changes.
The best-known examples occur among insects, which may exhibit complete or incomplete metamorphosis (see nymph ). The complete metamorphosis of butterflies, moths, and some other insects involves four stages: egg , larva ( caterpillar ), pupa (chrysalis or cocoon), and adult. The change from tadpole to frog is an example of metamorphosis among amphibians; some echinoderms, crustaceans, mollusks, and tunicates also undergo metamorphosis.