Common Protist Information

What Are Protists?

The kingdom Protista includes a diverse array of organisms, from minute flagellated cells to macroscopic (large) kelp. The smallest microscopic organisms are termed protists, consequently some biologists prefer to call this kingdom the Protoctista rather than Protista. 

Members of the kingdom Protista are not animals, which develop from an embryo called a blastula; they are not plants, which develop from an embryo that is not a blastula but is retained in the mother's tissue; they are not fungi which develop from spores and lack cilia and flagella (called undulipodia) at all stages of development; they are not monerans, which have prokaryotic (no nucleus) cells.

Protists are single-celled and usually move by cilia, flagella, or by amoeboid mechanisms. There is usually no cell wall, although some forms may have a cell wall. They have organelles including a nucleus and may have chloroplasts, so some will be green and others won't be. They are small, although many are big enough to be recognized in a dissecting microscope or even with a magnifying glass. Nutrients are acquired by photosynthesis, ingestion of other organisms, or both.


Protists belong to the Kingdom Protista, which include mostly unicellular organisms that do not fit into the other kingdoms.

Characteristics of Protists

mostly unicellular, some are multicellular (algae) can be heterotrophic or autotrophic most live in water (though some live in moist soil or even the human body) ALL are eukaryotic (have a nucleus) A protist is any organism that is not a plant, animal or fungus
Protista = the very first

Classification of Protists

How they obtain nutrition and how they move
Animallike Protists - also called protozoa (means "first animal") - heterotrophs (use movement to get their own food) - use locomotion
Plantlike Protists - also called algae - autotrophs (make their own food) - stationary
Funguslike Protists - heterotrophs, decomposers, external digestion (use what they live on for life support) - mostly stationary