Kalmar “genus” tana nufin rabe-raben haraji a cikin ilmin halitta wanda ya haɗa nau’ukan nau’ukan nau’i iri ɗaya. A wannan yanayin, "Daphnia" shine sunan jinsin ƙanana, crustaceans na ruwa waɗanda aka fi sani da ruwa. wani rukuni na nau'in ƙananan ɓawon ruwa na ruwa wanda aka fi sani da ruwa fleas, na gidan Daphniidae.
