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
Marine Biological Laboratory disease. Other marine organisms draw neuroscientists and neurobiologists to the MBL each summer, where a history of research into sensory physiology and behavior has been established. Haldan Keffer Hartline, an MBL summer investigator in the 1920s and early 1930s, uncovered several basic mechanisms of photoreceptor function through his studies on the horseshoe crab. Hartline shared the 1967 Nobel Prize with summer MBL colleague George Wald, who described the molecular basis of photoreception by showing that the light-sensitive visual pigment molecules consist of a slightly modified form of vitamin A coupled to a protein. Another long-term summer investigator, Stephen W. Kuffler,