Kalmar "Gregarinida" tana nufin wani nau'in protozoans na parasitic waɗanda ke cikin phylum Apicomplexa. Wadannan kwayoyin halitta yawanci suna zama a cikin hanyoyin narkewar abinci na invertebrates daban-daban, kamar kwari, crustaceans, da mollusks. Gregarinida suna da siffar elongated, jikinsu kamar tsutsa, wanda ya ƙunshi jerin sassan. Ba su da cilia ko flagella, amma suna da wata kwayar halitta ta musamman da aka sani da hadadden apical, wanda ke taimaka musu shiga cikin sel mai masaukinsu. Gregarinida mambobi ne masu mahimmanci na yawancin halittu masu rai kuma suna iya yin tasiri mai mahimmanci akan lafiya da dacewa da rundunansu.