Entamoeba, an amoeba that includes pathogens of the intestinal tracts of a range of hosts - humans are included. They have no mitochondria and seem to have adapted secondarily to an anoxic way of life. Cytoplasm of a thick and dense consistency, and like that of pelobionts (to which we think they are related) moves by fountain flow motion, passing up the middle of the cell and flowing out in all directions at the anterior end. Phase contrast. This picture was taken by David Patterson, Linda Amaral Zettler, Mike Peglar and Tom Nerad from cultures and other materials maintained at the American Type Culture Collection during 2001. Image copyright: D. J. Patterson, L Amaral-Zettler, M. Peglar and T. Nerad, image used under license to MBL (micro*scope).
Description of Entamoeba: Pseudopodia as semi-eruptive anterior bulges with clear hyaline caps. Endoplasm granular with vesicles but without crystals or contractile vacuole. Nucleus ring-like, with peripheral granules and a central endosome. Cysts round and smooth. Mature cysts of some species multinucleate. Many varieties reported. Habitat: parasite of the intestinal mucosa of man, apes, monkeys, dogs, cats, pigs, rats, cattle and other animals; some species commensal in mouth; can migrate to other tissues via the bloodstream; causes mild to severe diarrhoea on occasion lethal. Type species: Entamoeba coli Cassigrandi & Barbagallo, 1895.