Protists live in lakes, rivers, oceans, ponds and wet sediments. Since they are microscopic organisms, they can live in just about any part of the world that has traces of water to support their life.
Some of the most common groups of protists that can be found in rivers, lakes, oceans and other water bodies are:
Flagellates: They are the smallest in size when compared to other protists. They move by the use of flagella which propel them to wherever they wish to go.
Ciliates: Ciliates move by the use of fine hair-like features that are normally referred to as cilia. The cilia make them good swimmers, despite being the largest of the various groups of protists.
Sporozoa: These protists cannot move on their own since they do not have any features for movement. Sporozoa are generally parasitic in nature and thus rely on their hosts to move. They are likely to cling to animals like turtles and fish.
Heliozoans: Heliozoans are known to live in fresh water bodies like lakes rather than oceans. They are characterized by a lack of skeleton and stiff amoeboid pseudopods.
Other protists include amoebas and radiolarians.