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A Microbial Biorealm page on the Suctoria


Higher order taxa:

Eukaryota; Alveolata; Ciliophora; Phyllopharyngea


Discophyra collini
Tokophyra lemnarum
Heliophyra erhardi

NCBI: Taxonomy Genome

Description and Significance

Suctoria is one subclass of the class Phyllopharyngea. Although part of the phylum Ciliophora, Suctoria are perhaps most well-known as highly unusual members of this classification. Origianally, they were not thought to be ciliates, because they lack cilia at certain stages of life. In addition, Suctoria reproduction is atypical of most ciliates. Only at the larval stage do Suctoria bear much resemblance to other members of Ciliophora.

Genome Structure

Currently, there is not an extensive body of research on the genome structure of Suctoria.

Cell Structure and Metabolism

The ciliature of Suctoria is reduced in comparison to other ciliate organisms, so much so that they actually lack cilia in the adult stage of life. Instead, they have tentacles. Young swarmers have two rings of cilia. Scutoria are also grouped in Ciliophora because they are multinucleated. Once they shed their cilia, Suctoria become sessile; they attach themseleves to host organisms via a non-contractile stalk and develop tentacles. Suctoria are encased in a hard shell called the lorica. Another important characteristic of Suctoria is that they lack oral cavities. They use their tentacles as feeding mechanisms.

Suctoria are heterotrophs that feed on smaller ciliates. The tentacles are used both to capture prey and to suck nutrients out of them.

Scutoria reproduce by budding. Larvae form either at the top of the organism or in a brood chamber within the cell. A ciliated swarmer emerges from the tentacled adult; this resembles live birth found in mammals. Occasionally, Suctoria will reproduce by binary fission, but this is rare.


Suctoria are aquatic organisms, found most commonly in freshwater habitats. Some marine species form symbiotic relationships with crustaceans. For example, the Suctoria Flectacineta isopodensis is an epibiont of Excirolana chiltoni. Another Suctoria that forms such relationships is Ophryodendron mysidacii, an epibiont with the crustacean Schistomysis parkeri. Ophryodendron mysidacii can be found on different parts of the Schistomysis parkeri body, depending on what phase of the life cycle it is in. During the adult stage, Ophryodendron mysidacii can be found on uropods, abdominal segments, and eyes. At less mature stages, this organism is more likely to be found on the eyes and the basal area of antennae. However, Suctoria do not just form relationships with crustaceans. The species Ephelota gemmipara and Ephelota gigantea are epibionts of Lepeophtheirus salmonis (salmon louse), which is a parasite of Atlantic salmon (Salmo salar).

References. Updated June 22, 2005

Cavanihac, Jean-Marie. "Suctoria." Micscape Magazine. March 2003. Accessed 21 June 2005.

Esteban F, Tellez C, Munoz A. "Infraciliature, morphogenesis and life cycle of Endosphaera terebrans (Suctoria, Tokophridae)." J Protozool. 1991 Sep-Oct;38(5):483-8.

Fernandez-Leborans, Gregorio, Mark Freeman, Regina Gabilondo, and Christina Sommerville. "Marine protozoan epibionts on the copepod Lepeophtheirus salmonis, parasite of the Atlantic salmon." Journal of Natural History February 2005;39(8):587 - 596.

Fernandez-Leborans, Gregorio and Maria Luisa Tato-Porto. "Distribution of the protozoan epibiont Ophryodendron mysidacii
(Ciliophora, Suctoria) on the mysid Schistomysis parkeri (Crustacea)." Journal of Natural History, 2002, 36, 505–513.

Fernandez-Leborans, Gregorio, Yukio Hanamura, and Keizo Nagasaki. "A New Suctorian, Flectacineta isopodensis (Protozoa: Ciliophora) Epibiont on Marine Isopods from Hokkaido (Northern Japan)." Acta Protozool. (2002) 41: 79 - 84.

Matthews, Graham. "Pond Life: Protozoa. Part II: Ciliates." Accessed 22 June 2005.

Micrographia. "Suctoria." Accessed 21 June 2005.

Protist Information Server.

Rudzinska, Maria A. "Internalization of Macromolecules from the Medium in Suctoria." J . Celt. Biology. 1980 Jan;84(1):172-83.

Snoeyenbos-West OL, Cole J, Campbell A, Coats DW, Katz LA. "Molecular phylogeny of phyllopharyngean ciliates and their group I introns." J Eukaryot Microbiol. 2004 Jul-Aug;51(4):441-50.