(redirected from ciliate)
Also found in: Dictionary, Thesaurus, Medical, Wikipedia.
Related to ciliate: Ciliophora, paramecium, Sporozoa


(sĭl'ē-ŏf`ərə), phylum in the kingdom ProtistaProtista
or Protoctista
, in the five-kingdom system of classification, a kingdom comprising a variety of unicellular and some simple multinuclear and multicellular eukaryotic organisms.
..... Click the link for more information.
 consisting of the ciliates, or ciliophores, complex freshwater or saltwater protozoansprotozoan
, informal term for the unicellular heterotrophs of the kingdom Protista. Protozoans comprise a large, diverse assortment of microscopic or near-microscopic organisms that live as single cells or in simple colonies and that show no differentiation into tissues.
..... Click the link for more information.
 that swim by the coordinated beating of their cilia—short, hairlike structures that cover the cell surface. Like other protozoans, ciliates are unicellular heterotrophs. Some feed on bacteria and other particles as well as algae by means of cilia-created currents; many are carnivorous. In some species the cilia are organized into rows or clumps that the organisms use to walk or jump. Ciliates contain a variety of organelles plus two kinds of nuclei. The larger type of nucleus, the macronucleus, contains a great deal more DNA than the smaller nucleus, the micronucleus. Although the ciliates typically reproduce asexually, they also exchange genetic information with other ciliate cells by the process of conjugation. During this process two cells unite, the micronuclei undergo meiosis, then pair up and fuse with similar haploid micronuclei from the other organism, mixing the DNA from the two organisms.

There are approximately 8,000 species of ciliates. The phylum includes the slipper-shaped parameciumparamecium
, unicellular organism of the genus Paramecium, of the ciliate phylum Ciliophora found in freshwater throughout the world. Like other protozoans, paramecia, previously considered one-celled animals, are now customarily placed in kingdom Protista.
..... Click the link for more information.
 and the trumpet-shaped stentor. The suctorians are sessile ciliates that suck out the protoplasm of their prey through tentacles.


A subphylum of the Protozoa. The ciliates are a fairly homogeneous group of highly differentiated, unicellular organisms. Over 5000 species have been described, and many more surely exist but remain to be discovered. Typically, ciliates are larger than most other protozoans, ranging from 10 to 3000 micrometers (about 1/2500 to 1/8 in.). Some larger species are easily visible to the naked eye. The majority of them are free-living forms, found abundantly in a variety of fresh- and salt-water habitats, although a few entire groups live in association with other organisms, generally as harmless ecto- or endocommensals. Their principal value to humans is as experimental animals in a host of biological investigations.

The usual ciliate life cycle is fairly simple. An individual feeds and undergoes binary fission, and the resulting filial products repeat the process. Some commensal or parasitic forms have a more complicated life history. Some ciliates, including free-living species, have a cystic stage in their cycle. As in other kinds of Protozoa this stage often serves as a protective phase during adverse environmental conditions, such as desiccation or lack of food. It also may be important in distribution, and thus possibly in preservation, of the species.

Six major characteristics aid in distinguishing the Ciliophora from other protozoan groups. Not all of these are entirely unique, but when taken together they are definitely distinctive of ciliates: mouth, ciliation, infraciliature, nuclear apparatus, fission, and reproduction.

Most Ciliophora possess a true mouth or cytostome often associated with a buccal cavity containing compound ciliary organelles. However, some ciliates are completely astomatous, that is, mouthless. Nutrition is heterotrophic in ciliates.

The Ciliophora possess simple cilia or compound ciliary organelles, often in abundance, in at least one stage of their life cycle. Morphologically, cilia are relatively short and slender hairlike structures, whose ultrastructure is known, from electron microscope studies, to be composed of nine peripheral and two central fibrils. Membranes and membranelles are characteristically associated with the mouth or buccal areas and serve to bring food into the oral opening, although they sometimes aid in locomotion as well. See Cilia and flagella

Infraciliature is present, without exception, at a subpellicular level in the cortex. The infraciliature consists essentially of basal bodies, or kinetosomes, associated with cilia and ciliary organelles at their bases, plus certain more or less interconnecting fibrils.

Ciliophora possess two kinds of nuclei, and at least one of each is usually present. The smaller, or micronucleus, contains recognizable chromosomes and behaves much as the single nucleus in cells of metazoan organisms. The larger, or macronucleus, is considered indispensable in controlling metabolic functions, and is recognized as having genic control over all phenotypic characteristics of ciliates.

Ciliophora exhibit a type of binary fission commonly known as transverse division. In ciliates the splitting results in two filial organisms, the anterior or proter and the posterior or opisthe which, geometrically speaking, show homothety with respect to identical structures possessed by each. Thus, homothetogenic is both a broader and most exact descriptive term.

Ciliophora lack true sexual reproduction. Ciliates do not show syngamy, with fusion of free gametes. Processes such as conjugation are considered to be sexual phenomena, since meiosis and chromosome recombination are involved, but not sexual reproduction. In addition to conjugation, certain ciliates exhibit forms of sexual phenomena known as autogamy and cytogamy. See Protozoa, Reproduction (animal)


(invertebrate zoology)
The ciliated protozoans, a homogeneous subphylum of the Protozoa distinguished principally by a mouth, ciliation, and infraciliature.
References in periodicals archive ?
New insights into the phylogeny of eukaryotes based on ciliate Hsp70 sequences.
Ciliates are the dominant grazers on pico- and nanoplankton in a shallow, naturally highly eutrophic lake.
Polymerase Chain Reaction Amplification, Cloning, and Sequencing of 18S rRNA Genes from the Georgia sBG Ciliate and Synophrya sp.
Posterior face with 3 rows of finely ciliate or denticulate setae, distal row with 3+3 setae (Fig.
Revealed quantitative predominance of attached ciliates (Epistylis, Opercularia, and Vorticella), occurrence of hypotrichs and predatory ciliates (Litonotus, Amphileptus), suctorians (Tokophria, Podophria), testate amoebae (Arcella and Centropyxis), the constant presence of rotifers, the presence of significant quantities of Oligochaeta of the Aeolosoma kind is an indicator of the process of nitrification of activated sludge, when the main part of the organic substrate has already mineralized.
Terminology for orientatiton used in describing the structure of the ciliate species conforms to the conventional system of ciliate phylum proposed by Dogiel (1927).
Ability of the rumen ciliate Epidinium ecaudatum to digest and use crystalline cellulose and xylan for in vitro growth.
Mesembrinella (according to Guimaraes 1977) differs from the other genus of Mesembrinellinae in the following combination ofcharacters: humeral callus with three setae; post humerals present; two of three katepistemal setae and remigium from ciliate to bare.
BRAGHIROLI (2007): <<Changes in the ciliate assemblage along a fluvial system related to physical, chemical and geomorphological characteristics>>, European Journal of Protistology, vol.