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Flagellates and ciliates are polyphyletic protists conveniently placed in two groups based on their means of motility. Some are photosynthetic, many or most are heterotrophic phagotrophs.

Flagellates most commonly have two emergent flagella, each with elongate and parallel contractile microtubules arranged in a '9+2' arrangement of bundles - in cross section there are nine peripheral and two central bundles that extend the length of the flagella. Some flagellates have on flagellum, others have four or more. In addition various sub-groups (classes) have short hair-like appendages, often arranged in one or two rows along one of the flagella while the other flagellum is shorter or less active and lacks the appendages (called 'mastigonemes' or 'tinsel' in older literature. Many flagellates are mixotrophs capable of osmotrophy, phagotrophy and phototrophy. Photosynthetic genera are grouped based on their type of chlorophyll (a+b, a+c) and storage of starch or lipid.

Ciliates have variable numbers of pairs of 'cilia' which have a structure similar to or identical to flagella. Most of them also have an oral cavity generally with a concentration of cilia nearby on the cyto-membrane. 'Food vacuoles' develop around ingested particles. Many ciliates maintain a population of photosynthetic 'zoochlorellae' that become a partial or complete food supply.



Leadbeater, B.S.C., and J.C. Green (Ed.) 2000.  The Flagellates – Unity, diversity and evolution.Taylor & Francis (401 pp).

Lynn, D.H. 2008. The ciliated protozoa -- Characterization, classification, and guide to the literature. Springer Science + Business Media B.V. (605 pp.)

Patterson, D.J. 1996. Free-living freshwater protozoa – A colour guide. UNSW Press, Sydney. (223 pp.)