Aliivibrio fischeri (also called Vibrio fischeri) is a Gram-negative, rod-shaped bacterium found globally in marine environments. "A. fischeri" has bioluminescent properties, and is found predominantly in symbiosis with various marine animals, such as the Hawaiian bobtail squid. It is heterotrophic, oxidase-positive, and motile by means of a single polar flagella. Free-living "A. fischeri" cells survive on decaying organic matter. The bacterium is a key research organism for examination of microbial bioluminescence, quorum sensing, and bacterial-animal symbiosis. It is named after Bernhard Fischer, a German microbiologist.