Life Cycles - Introduction

Introduction

All animals go through changes during their lives. Some simply grow larger, while others completely change their forms. This kind of change is called metamorphosisTransformation of an immature animal into an adult., which means "change in form."

Some insects have no metamorphosis, simply growing larger and becoming able to reproduce. Others undergo an incomplete metamorphosisMetamorphosis in which a nymph form gradually becomes an adult through molting., in which the immature insects are known as nymphsAn immature form in the life cycle of insects that go through an incomplete metamorphosis.. Nymphs, which often live in water, resemble the adult forms, but their wings are not fully developed and they have no reproductive organs. Nymphs gradually become adults by moltingShedding of the outer layer of an animal, as occurs during growth of insect larvae., or shedding their outermost layer.

Other insects go through a complete metamorphosisMetamorphosis in which a larva becomes a pupa before changing into an adult form., in which the immature stage is called a larvaImmature form (worm-like in insects; fishlike in amphibians) of an organism capable of surviving on its own. A larva does not resemble the parent and must go through metamorphosis, or change, to reach its adult stage.. Caterpillars, for example, are the larvae of butterflies. The larva becomes a pupaA stage in the metamorphosis of an insect during which its tissues are completely reorganized to take on their adult shape., which is mostly a resting stage. Finally, the pupa emerges as a full-fledged adult, such as a

butterfly. Organisms in different stages of the life cycle often live in different habitats and eat different foods.