The two characteristics of the phylum Protozoa are:
Unicellularity: All protozoans are unicellular organisms, which means they are made up of a single cell. Despite being single-celled, they exhibit a range of complex behaviors and adaptations.
Heterotrophic nutrition: Protozoans are heterotrophic, which means they obtain their nutrients from other organisms. They may be parasitic or free-living, and feed on bacteria, other protozoans, or organic matter.