Stentor sp. protozoan, differential interference contrast (DIC) light micrograph. Stentor is a genus of large, single-celled, freshwater protozoans that are commonly found in ponds, lakes, and slow-moving streams. They are characterised by their trumpet-shaped body, which can be up to several millimetres in length, and their cilia, which they use for movement and feeding. Stentor is a highly adaptable organism, able to survive in a range of environmental conditions. It feeds on bacteria and other small organisms, which it captures using its cilia and sweeps into its mouth at the base of its body. One of the most striking features of Stentor is its ability to undergo rapid changes in size and shape in response to changes in its environment. When conditions are favourable, it can grow rapidly and develop multiple nuclei within its body. However, when conditions become unfavourable, it can contract its body and enter a dormant state known as an encystment, in which it forms a protective membrane around itself to survive periods of drought or other stresses. Stentor is also notable for its regenerative abilities. When a Stentor cell is cut or injured, it can regenerate the missing parts of its body within a matter of hours, a process that is facilitated by its multiple nuclei and ability to rapidly divide its cells. Due to their unique and fascinating characteristics, Stentor and other protozoans like it have become important model organisms for research in cell biology and genetics. They are commonly studied in laboratory settings, where their rapid growth and regenerative abilities make them valuable tools for investigating a range of biological processes.