The Class Gastropoda is one of the most morphologically and functionally diverse groups of living organisms. The diversity is even greater when major morphological (and implied functional) departures are added in from the more than 500 million years of fossil record of the group. There are a number of good basic illustrated accounts of the comparative morphology of the shell, external and internal anatomy, and radula (see especially Cox, 1960; Fretter and Graham, 1962; Hyman, 1967). There are no corresponding accounts of function. Accounts of gastropod ecology, behavior, and life habits are traditionally treated separately and outside of the morphological framework. As a result, the terminology and classification systems developed to describe gastropod form are separate from those dealing with gastropod function.