Vorticella feeding. Light microscopy footage of Vorticella campanula, a ciliate protozoan. This clip shows a close-up of the bell-shaped head and peristome (opening) that is lined with two rows of cilia. The ciliary movements cause a water current that carries microscopic algae, bacteria and other food into the buccal cavity (infundibulum). This clip shows active food selection and rejection. Vorticella live in both marine and freshwater environments. This is a freshwater specimen.