This clip shows two cells of the protist Euglena. Euglena and closely related protists are characterized by having a pocket at their anterior end from which a flagellum emerges. In this clip, the use of phase contrast microscopy allows you to view the flagellum at the rounded anterior end; the posterior end is more pointed. These cells are anchored at the posterior end by nail polish so that you can see their swimming behavior. The tiny specks swarming around them are bacteria, enabling you to compare the relative size of prokaryotes and eukaryotic protists. Credit: Michael Clayton, University of Wisconsin, Madison.