The Protists-Eukaryotic Organisms Kingdom Protista Single-celled, eukaryotic organisms are called protists. They are grouped together in Kingdom Protista. Those protists that are animal-like are put in Subkingdom Protozoa, and the protists that are plantlike belong to Subkingdom Algae. The Protists â Subkingdom Protozoa Members of Subkingdom Protozoa, known as the protozoans, have a cell membrane (the pellicle) but lack cell walls.