Our planet is also home to living organisms that are more primitive than plants, animals and fungi. Because these unicellular organisms cannot be classified in any other kingdom of living organisms, they are considered as their own group, called protists.

Protists are not related to one another. Many microscopically small living organisms, such as the malaria parasites and amoebas, are protists.

The image on the right shows a protist known as a paramecium. It is an unicellular organism found in water ecosystems.