Protozoa are unicellular, eukaryotic, heterotrophic organisms. They are either free-living or parasites. There are around 65000 species of protozoans categorised in different groups.
- They live in the freshwater, sea or moist soil.
- The movement is by pseudopodia. They capture their prey by pseudopodia
- There is no definite shape and pellicle is absent
- The contractile vacuole is present in the amoeboid living in freshwater
- Reproduction is by binary fission and cyst formation