Stentor is a trumpet-shaped single-cell freshwater ciliate. One of the largest prootozoans, Stentor can be up to 2mm long.

Stentor lives a mostly sedentary lifestyle, attached to substrates by a sticky substance produced at its narrow end. It can detach and swim freely using rows of cilia along its body.

Stentors are highly contractile. Contraction and extension are controlled by two longitudinal fiber systems in the cell cortex. Cilia lining the “horn of the trumpet” beat rhythmically, creating currents that collect food. Stentor typically feeds on bacteria and other protozoans.

A contractile vacuole collects excess water and waste, periodically discharging them from the organism. This process helps balance higher salt concentration inside the Stentor.