Carchesium Ehrenberg 1831

Genus of sessile peritrich ciliates, forms tree-like colonies which can reach 4mm in height. There may be over one hundred bell-shaped cells (zooids) supported by branches of the stalk, each of which has a separate contractile myoneme and is capable of independent contraction. Typical peritrichous oral ciliature consisting of anticlockwise spiraling kineties at the anterior end of the cell. Somatic ciliature is absent, typical of the order Peritrichida. Usually there is a ribbon-like macronucleus. Habitat and distribution: freshwater and marine, often found as ectocommensals on aquatic organisms. Common.

Carchesium is a genus of usually colonial peritrich ciliates in the Vorticellidae with a spirally contractile stalk. The inverted bell-shaped cells have an oral lip as in Epistylis

The genus has a cosmopolitan diribution in freshwater and is a common part of the fauna of the aerobic stages of waste water treatment plants, such as activated sludge and trickling filters.