freshwater protozoan of the class Zoomastigophorea. Helioflagellates sometimes are considered relatives of the heliozoans (heliozoan) (organisms having pseudopodia but no flagella) because of their slender radiating cytoplasmic masses called pseudopodia. The cores of the pseudopodia of some genera of helioflagellates radiate from a central granule, as they do in some heliozoans. Helioflagellates' life cycles involve alternations between flagellate and heliozoan phases. They reproduce asexually by binary fission. Members of the representative genus Ciliophrys are spherical in shape and have a flagellum and very slender pseudopodia; those of the genus Dimorpha are oval in shape. Formerly, helioflagellates were classified as the order Helioflagellidia (subphylum Sarcodina).