of its host while cysts are more resilient and can survive in the external environment in habitats such as water, awaiting to be ingested by the next host. Parasitic Hosts Retortamonas trophozoites have been found to feed on the intestinal bacteria of a wide variety of vertebrates including mammalian, avian, and amphibian hosts, as well as invertebrates, such as insects. Recent evidence however, suggests that species infecting insects are in fact Chilomastix. Life Cycle Retortamonas has a direct life cycle as it infects a single host without requiring an intermediate or vector to complete its life cycle. Cysts live in the external environment and possess a thickened cyst wall which functions to protect the cell in the harsher habitats during its time away from a host. Cysts are ingested via the fecal-oral route, commonly from contaminated food, water or other materials likely to carry infection. Once in the intestine of its host, cysts undergo excystation into the trophozoite stage that feeds on intestinal bacteria. Each cyst gives rise to only one trophozoite. Retortamonas trophozoites then multiply asexually through lateral binary fission. Eventually the trophozoites encyst, and the cysts are discharged via feces. The cysts are usually found living in food and water while they wait to be taken up by the next host and continue the spread of transmission via the fecal-oral route. Feeding Mechanisms Retortamonas feed on intestinal bacteria in the gut of the host. The trophozoites feed by endocytosis with the help of the posterior, vaned flagellum. Movement in a waving-like motion by the flagellum brings food particles inwards, towards the cell. Retortamonas is then able to engulf them into the cell and form an internal food vacuole. The cyst stage's main function is to survive in the external environment away from the host and spread transmission rather than feeding, coinciding with the fact it has no availability to a food source as it is located away from the intestine of its host. Pathogenesis Retortamonas is non-pathogenic. Since this genus has not been discovered to cause any disease, it has been classified as a harmless commensal. Diagnosis Infection is commonly detectable by the presence of cysts or trophozoites in fecal samples. The probability of finding either or both the cyst and trophozoite stage in feces is very low, and often up to thousands of samples are required before detection is achieved. Since this genus does not cause any