Entamoeba
The
entamoebae group of parasitic and commensal
amoebae. Entamoebae are uninucleate and small, usually 10-100 μm across, and are typically monopodial with lobose pseudopods taking the form of clear
anterior bulges. Cysts are common. This is one of the few groups that lack
mitochondria, which is probably a secondary loss associated with their parastic life style; the cells do contain
dictyosomes, which are generally supposed to have evolved later. The best known member is
Entamoeba histolyca, which is responsible for
amoebic dysentery in humans in other
mammals. Another well-known species is
Entamoeba coli, which is relatively harmless.