Amoeboid protozoan are distinguished by the presence of flowing extensions of their body known as pseudopodia. These are used for feeding and locomotion. The pseudopodia are given different names according to their shape and structure. This group includes the familiar Amoeba and other marine, fresh water and terrestrial taxa. The amoeboid form may be the result of retention of the ancestral protistan condition in some species. In some others it may be secondarily acquired through loss of flagella, as many groups have flagellated gametes in their life cycle.
Amoeboid protozoan are either asymmetrical Or show spherical symmetry. They possess relatively few organelles and may be the simplest of the protozoan. However the majority of the species have evolved complicated skeletal structures that make them uniquely beautiful organisms. There are four principal groups of amoeboid protozoan: amoebae, foramlnlferans, helizoans and radiolarians. Of these the amoebae and foramlniferans belong to superclass Rhizopoda while the radiolarians and helizoans belong to superclass Actinopoda, as they have axopods.