Most protozoa can be viewed as free-living or symbiotic.
• For the former, they are found in soil or aqueous environments.
• For symbionts, they live in close association with another organism.
Commensalism:
Many protozoa live in alimentary tract of another organism
without harming it. They are often scarvengers.
Mutualism:
Trichonympha found in the gut of termites digests the wood
particles ingested by the termite.
Parasitism:
The parasites will be harmful to the host and referred to as
being pathogenic.