ciliate - Classification

A microscopic, single-celled organism typically possessing short hair-like appendages (cilia) on its surface; contains two types of nucleus (macronucleus and micronucleus); commonly also with a specialized mouth region (cytostome); found free-living in all kinds of aquatic and terrestrial habitats, and as parasites. (Phylum: Ciliophora.)

?Ciliates
"Ciliata" from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification
Kingdom: Protista Phylum: Ciliophora Doflein, 1901 emend.
Classes
Karyorelictea Heterotrichea Spirotrichea Litostomatea Phyllopharyngea Nassophorea Colpodea Prostomatea Oligohymenophorea Plagiopylea See text for subclasses.

The ciliates are one of the most important groups of protists, common almost everywhere there is water — lakes, ponds, oceans, and soils, with many ecto- and endosymbiotic members, as well as some obligate and opportunistic parasites.

Unlike other eukaryotes, ciliates have two different sorts of nuclei: a small, diploid micronucleus (reproduction), and a large, polyploid macronucleus (general cell regulation). Food vacuoles are formed through phagocytosis and typically follow a particular path through the cell as their contents are digested and broken down via lysosomes so the substances the vacuole contains are then small enough to diffuse through the membrane of the food vacuole into the cell. Most ciliates also have one or more prominent contractile vacuoles, which collect water and expel it from the cell to maintain osmotic pressure, or in some function to maintain ionic balance.

Most ciliates feed on smaller organisms (heterotrophic), such as bacteria and algae, and detritus swept into the mouth by modified oral cilia.

In some forms there are also body polykinetids, for instance, among the spirotrichs where they generally form bristles called cirri. Another are the alveoli, small vesicles under the cell membrane that are packed against it to form a pellicle maintaining the cell's shape, which varies from flexible and contractile to rigid.

Classification

Phylum Ciliophora

Class Karyorelictea Class Heterotrichea (e.g. Stentor) Class Spirotrichea Subclass Choreotrichia (e.g. Tintinnidium) Subclass Oligotrichia (e.g. Halteria) Subclass Stichotrichia (e.g. Stylonychia) Subclass Hypotrichia (e.g. Euplotes) Class Litostomatea Subclass Haptoria (e.g. Didinium) Subclass Trichostomatia (e.g. Balantidium) Class Phyllopharyngea Subclass Phyllopharyngia Subclass Rhynchodia Subclass Chonotrichia Subclass Suctoria (e.g. Podophrya) Class Nassophorea Class Colpodea (e.g. Colpoda) Class Prostomatea (e.g. Coleps) Class Oligohymenophorea Subclass Peniculia (e.g. Paramecium) Subclass Hymenostomatia (e.g. Tetrahymena) Subclass Scuticociliatia Subclass Peritrichia (e.g. Vorticella) Subclass Astromatia Subclass Apostomatia Class Plagiopylea