1. Protozoa are unicellular, eukaryotic organisms belonging to kingdom, Protista.
2. They are microscopic of the size of about 200 pm.
3. They have different organs of locomotion such as pseudopodia, cilia and flagella.
4. Reproduction is by asexual method, usually by binary fission.
5. Protozoa are seen in varied habitats such as soil, fresh water and marine water.
6. Some protozoans are parasitic and cause various types of illness in hosts. E.g. Entamoeba histolytica is a species of amoeba that causes amoebiasis. Malaria is caused by Plasmodium vivax.
7. Protozoa show different modes of nutrition.
E.g. Euglena is autotrophic as it does photosynthesis with the help of 5 chloroplasts present in its body. Amoeba and Paramoecium are heterotrophic and free living seen in contaminated water.
