Protozoa are classified into three groups based on their shape. Ciliates are the largest and move by means of hair like cilia. They eat the other two types of protozoa, as well as bacteria. Amoebae also can be quite large and move by temporary foot. Amoebae are further divided into testate amoebae that make a shell like covering and naked amoebae without a covering.
Flagellates are the smallest of the protozoa and use a few whip like flagella to move.
In amoeba, actin and myosin are organized into a three dimensional network. Locomotion in amoeba is brought about by the continuous assembly and disassembly of actin and myosin containing complexes. As a result of this activity, pseudopodia are formed at the front end of the moving cell. Movement in the ciliates is accomplished through the action of cilia which cover the surface of the organism and function somewhat like oars. Flagellates movement is accomplished through a whip-like action of the flagella.