Marine life live in the water column of large bodies of water and that cannot swim against a current. They provide a crucial source of food to many large aquatic organisms, such as fish and whales. These organisms include drifting or floating bacteria, archaea, algae, protozoa and animals that inhabit, for example, the pelagic zone of oceans, seas, or bodies of fresh water. Essentially, plankton are defined by their ecological niche rather than any phylogenetic or taxonomic classification. Though many planktonic species are microscopic in size, "plankton" includes organisms covering a wide range of sizes, including large organisms such as jellyfish. The
Malacological Society of London 1942. Molluscs range in size from cephalopods such as the octopus and giant squid to microscopic gastropod snails, and the Society is concerned with some 85,000 recognised extant species, which include 23 per cent of all named marine organisms as well as molluscs living in freshwater and terrestrial habitats. It is also interested in the species (including those of the two extinct classes of molluscs) preserved as fossils, which creates a relationship with the study of geology. In association with the Oxford University Press, the Society publishes the "Journal of Molluscan Studies", previously called "Proceedings of the Malacological Society", and