Functional morphology involves the study of relationships between the structure of an organism and the function of the various parts of an organism. The old adage "form follows function" is a guiding principle of functional morphology. The function of an organ, appendage, tissue, or other body part dictates its form. Furthermore, the function can often be deduced from the form. The idea of relating form and function originated with the French naturalist Georges Cuvier (1769-1832).

The primary task of functional morphology is observing living organisms to see how they live and function. From observations of living organisms, scientists also attempt to discern principles that will allow them to determine function from the forms of fossils, such as bones, shells, or whatever happens to be preserved from organisms that no longer exist. Theoretical morphology tries to determine the limits of form; not every conceivable form could actually...