Metridinidae is a family of copepods, comprising three genera – Gaussia, Metridia and Pleuromamma.[1] It has also been referred to as "Metridiidae", but following a petition to the International Commission on Zoological Nomenclature, that name has been restricted to the family Metridiidae Carlgren, 1893, based on the anthozoan genus Metridium.[2] All species in the family can produce blue-green bioluminescence; the light is produced in glands, whose position varies between genera.[3]