Included in the group are some which may also be classified as plants, the distinction being that these possess chlorophyll.
A protozoan can be any of a diverse group of eukaryotes (organisms composed of one or more cells, each of which contains a clearly defined nucleus enclosed by a membrane, along with organelles [small, self-contained, cellular parts that perform specific functions]), of the kingdom Protista, that are primarily unicellular, existing singly or aggregating in colonies, are usually nonphotosynthetic, and are often classified further into phyla according to their capacity for and means of motility, as by pseudopods, flagella, or cilia.
Are short, or long, or round like fritters;
They go through life with but one cell
And seem to manage very well.
Protozoa exist throughout aqueous environments and soil, occupying a range of trophic (nutritional) levels. As predators, they prey upon unicellular or filamentous algae, bacteria, and microfungi.
Protozoa play a role as both herbivores and consumers in the decomposer link of the food chain.
Protozoa also play a vital role in controlling bacteria populations and biomass and they may absorb food via their cell membranes, some; for example, amoebas, surround food and engulf it, and yet others have openings or "mouth pores" into which they sweep food.
All protozoa digest their food in stomach-like compartments called vacuoles.