The fine structure of a carnivorous multiflagellar protist, Multicilia marina Cienkowski, 1881 (Flagellata incertae sedis)

A light and electron microscopical study of a carnivorous multiflagellate m arine protist, Multicilia marina Cienkowski, 1881, is performed. Cells in c ulture roll over the substratum without any polarity, and have normally 20- 30 long flagella beating more irregularly and without visible coordination; a peculiar formation of small cells with 2-4 flagella and giant, branching and budding ones with 100-200 flagella is described. Ultrastructural study shows the cells to be covered with a free glycocalyx, to have a single cen tral nucleus, mitochondria with tubular cristae, and to have no modificatio ns in the cortical cytoplasm. The basal apparatus of each flagellum is repr esented by a single kinetosome, an open conical microtubular sheath surroun ding it, and a microtubular fiber connecting each kinetosome with the sheat h of a neighbouring one. No structural connection between the basal apparat us and the centrally located nucleus has been observed. The structure of th e flagellar apparatus is compared with that in other multiflagellate/ciliat e protists. The irregular movement of Multicilia seems to result from its a daption to capturing its main food - naked amoebae. A new phylum Multiflage llata is proposed to include the genus Multicilia, the diagnosis of M. mari na is amended on the base of present observations.