For example , the term protozoa is used to refer to heterotrophic species of protists that do not form filaments .
However , the older terms are still used as informal names to describe the morphology and ecology of various protists .
The term protozoa is used to refer to heterotrophic species of protists that do not form filaments .
However , the older terms are still used as informal names to describe the morphology and ecology of various protists .