The Vorticella is a sessile, ciliate protozoan of the order Peritricha. Each single celled individual has a head or zooid and a retractable stalk which anchors it to the substrate. The flattened top of the head bears the mouth and a complicated wreath of hair-like cilia. The beating of the cilia creates tiny vortices in the water which wash bacteria into the organism's mouth. Magnification is x70 at 35mm.