Ciliates use cilia for locomotion, similar to the way flagella are used in flagellates.

Ciliates use “flagella” for feeding and movement.

0.4 to 2 mm s-1
“Ciliates swim faster than flagellates. Speeds of 0.4 to 2 mm s-1 are usual, while flagellates can only achieve 20-200 µm s-1.”

Ciliates are minute, single-celled organisms with several nuclei, and are abundant in freshwater, the oceans and soil. Many organisms are known which use sulfur-oxidizing bacteria as a source of energy. The first were found by pure chance near the hydrothermal vents in the deep sea in the 1970s.

Most ciliates are heterotrophs, feeding on smaller organisms, such as bacteria and algae, and detritus swept into the oral groove (mouth) by modified oral cilia. The food is moved by the cilia through the mouth pore into the gullet, which forms food vacuoles.

In fact, some biologists consider the ciliates to be acellular (not cellular) rather than unicellular in order to emphasize that their “body” is far more elaborate in its organization than any cell out of which multicellular organisms are made. Ciliates have: at least one small, diploid (2n) micronucleus.

Feeding. Most ciliates are heterotrophs, feeding on smaller organisms, such as bacteria and algae, and detritus swept into the oral groove (mouth) by modified oral cilia. The food is moved by the cilia through the mouth pore into the gullet, which forms food vacuoles. Feeding techniques vary considerably, however.

Although most ciliates are free-living and aquatic, such as the Paramecium (q.v.), many are ectocommensals, dwelling harmlessly on the gills or integument of invertebrates, and some, such as the dysentery-causing Balantidium (q.v.), are parasitic.

2. Ciliates. Although a few ciliates are mixotrophic and supplement nutrition by photosynthesis, most are holozoic and feed on bacteria, algae, particulate detritus, and other protists.

The only ciliate that causes human disease is Balantidium coli. Infections of the intestinal parasite, apparently rare, is from pigs.

… is a suspension-feeding ciliate that lives in two forms: free swimming telotroch and sessile stalked trophont [4].

Ciliates are heterotrophs, being either phagotrophs or osmotrophs.

Whole orders and multispecific genera of ciliates are obligate ectosymbionts on specific molluscs and crustacea.

Ciliates are unicellular protists that on phylogenetic trees diverge together with apicomplexan parasites and dinoflagellates, all members of the alveolates. The ciliates are a diverse monophyletic group, with certain species estimated to be as evolutionarily distant from one another as corn from rats.

Free Swimming and Crawling Ciliates. Some ciliates have specialized cilia that look and function like legs, allowing them to crawl around on floc particles and “flick” up the bacteria so that they can consume them. These are called crawling ciliates and tend to stay on the floc more than free in the bulk water.

The main purposes of their cilia are to propel the organisms and to gather food into their mouths (cytostome). They feed mostly on bacteria and other single cell organisms. They are sometimes identified by their smooth gliding or “swimming” motion through a sample or by the “crawling” movements around a piece of floc.