Marine Faunal Dominance and Molluscan Shell Form

One of the most important ecological problems facing mankind is predicting the effects of breaking down barriers on a large scale between previously separated marine or terrestrial biotas. While opinions on this subject are numerous and conflicting, few data are available and little predictive theory has been developed (see Elton, 1958; Remington, 1967; Rubinoff, 1968; Topp, 1969; Por, 1971; Vuilleumier, 1971; Fooden, 1972). In this paper I examine in a hypothetical way the possible consequences of a proposed sea-level canal across the Isthmus of Central America (Rubinoff, 1968; Topp, 1969) in the light of differences in shell architecture among shallowwater marine molluscan assemblages which I believe to reflect differences in the ability to withstand predation.