A unicellular protoctist of the phylum Ciliophora, whose members are usually covered in short undulipodia (cilia) and have two different kinds of nuclei, micronuclei and macronuclei.

• 2纤毛虫：纤毛虫纲的一类原生单细胞生物。该类生物具有短的纤毛，还具有两个细胞核，一个是大核，另一个是小核。