Ciliate biology

A macronucleus (formerly also meganucleus) is the larger type of nucleus in ciliates. Macronuclei are polyploid and undergo direct division without mitosis. It controls the non-reproductive cell functions, such as metabolism. During conjugation, the macronucleus disintegrates, and a new one is formed by karyogamy of the micronuclei.

thumb|Paramecium tetraurelia, a ciliate, with discharged trichocysts (artificially colored in blue). A trichocyst is an organelle found in certain ciliates and dinoflagellates.

thumb|Micronuclei visible in boxes|280x280px

shell-like protective outer covering