Host-Parasite Relationships

• Symbiosis - the "living together" of unlike organisms; involves protection or other advantages to one or both organisms.
• Commensalism - two species live together and one species benefits from the relationship without harming or benefiting the other
• Mutualism - two organisms mutually benefit from each other
• Parasitism - one of the organisms, the parasite, either harms its host or lives at the expense of the host
• Entamoeba coli and Entamoeba gingivalis - parasites that exhibit commensalism
• Entamoeba histolytica - a pathogenic amoeba that causes amoebic dysentery and is associated with intestinal and extraintestinal infections; exhibits parasitism
• Termites - exhibit mutualism with their intestinal protozoan flagellates (Trichonympha sp.)
• Trichonympha sp. - synthesize cellulase to aid in the breakdown of ingested wood