Not all protozoa are harmful. For example, the [[The Rumen - Anatomy & Physiology|rumen]] of ruminants and the [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]] of horses are full of symbiotic protozoa. | Not all protozoa are harmful. For example, the [[The Rumen - Anatomy & Physiology|rumen]] of ruminants and the [[Caecum - Anatomy & Physiology|caecum]] and [[Colon - Anatomy & Physiology|colon]] of horses are full of symbiotic protozoa. |