Ecology of marine mollusks contains some of the communications presented at the Symposium on Ecology of Molluscs, within the Twelfth International Malacological Congress held in Vigo (Spain) from September 3rd to September 8th, 1995. These articles deal with different groups of marine molluscs from several ecosystems and embrace different aspects of their ecology: There are studies on trophic ecology (feeding dynamics, commenwalism and endo-symbiosis of gastropods, bivalves and cephalopods), demographic ecology (in varied aspects such as population structure, survival, growth, reproduction and competition) and descriptive ecology (migration of cuttlefish using marking techniques, larval phenology and fish-cephalopod relationships), together with biogeography and the study of the impact of human exploitation of ecosystems over molluscs.