This Journal of Bacteriology mini-review explores specificity in the Vibrio fischeri-Euprymna scolopes partnership. Euprymna scolopes hosts a symbiotic colony of the bioluminescent bacterium Vibrio fischeri as a sophisticated anti-predation measure. During its nocturnal feeding period, the squid emits light downward and modulates it to match the intensity of moonlight, thus preventing the formation of a telltale shadow on the ocean floor below. Maintenance of this bioluminescent bacterial partner is therefore important for survival of the squid, which has evolved a special organ in the center of its body cavity for promoting growth of the bacteria and controlling the emission of light. This mini-review places the role of specificity in the development of cooperative light organ symbiosis into a conceptual framework. It reviews the nature of the landscape and the scale over which the process of colonization takes place by putting into context the relationship of the bacterial macro-ecology to the micro-ecology of the host's body cavity.
