Most organisms change dramatically in size, shape and behavior as they mature. The most striking changes occur in those species that have complex life cycles. Variation may occur in a single individual as it matures, as in the transition from a tadpole to a frog, or may result from an alternation of generations from one life form to another as in many plant groups or in the jellyfishes and their relatives. You will study individual life cycles in more detail in later exercises. Note the considerable variation that is seen in a single species at various points in its life cycle.
Examples of variation with age: