This leads in turn to an increase in the population of protozoa such as Stentor which feed on the bacteria. Colonies of Stentor often occur, in which the lower parts of the animals are covered with a mucilaginous substance which they secrete. This capability has made Stentor a favourite subject amongst biologists for studies of regeneration in protozoans. The image at the top of this page shows a typical view of a Stentor using bright field illumination. When attached to a substrate, the Stentor has a trumpet shape.
Any disturbance makes the whole body contract to become a blob of protoplasm.
The image to the left shows Stentor when swimming where it adopts an oval or pear shape. To find new feeding grounds, the animal swims by means of cilia that cover the body. Stentor can be very colourful - there are green, blue and amethyst coloured species. The figure on the left shows a green form using dark field illumination. The green colour is a result of the microscopic green algae which Stentor ingests.