Many also have a sexual stage. Whittaker's classification places algae, in the kingdom called Protista. Our microbiology class discussed 13 different species of pathogenic or disease causing protozoa this semester. The 13 species are divided into four classes and the classes are distinguished by the method of locomotion that the protozoa uses. Two organisms of protozoa that make up this class are Entamoeba histolytica and Naegleria Fowleri, also known as the causative agents for amebiasis.
Amebiasis occurs throughout the world from tropical to subpolar.
The organism enters the body by food or water contaminated with feces, or by contact with feces. Entamoeba histolytica has the ability to destroy tissue by penetrating the walls of the small and large intestine. All members of this class move by one or more whip like, undulating flagella. The protozoa adhere to the intestinal lining, multiply rapidly, and the patient experiences nausea, gastric cramping, and diarrhea that lasts for weeks. The third class Ciliphora is described as being among the most complex cells on earth, and the organism Balantidium coli is one of the few members of the class that causes human disease.