Amoebae move by amoeboid movements, small projections and invaginations of their plasma membrane (pseudopods) that alter the external morphology of the cell making it move on surfaces. Paramecia have the outer face of their plasma membrane covered by cilia that flap helping the cell to move. Trichomonas are flagellated protozoans, i.e., they have relatively long filaments outside the cell that beat and make possible active swimming in fluid environments. Protists Review - Image Diversity: amoeboid movement