Kalmar "Cyanophyceae" tana nufin phylum na kwayoyin cuta da aka fi sani da cyanobacteria ko blue-green algae. Wadannan kwayoyin halitta hotuna ne kuma galibi ana samun su a wurare daban-daban na ruwa. Kalmar "Cyanophyceae" ta fito ne daga kalmomin Helenanci "kyanos," wanda ke nufin blue, da "phyton," wanda ke nufin shuka. Wannan phylum ya ƙunshi nau'ikan nau'ikan sama da 2,000, wasu daga cikinsu suna da mahimmanci don rawar da suke takawa wajen gyara nitrogen da samar da iskar oxygen ta hanyar photosynthesis.