Suctoria on green algae. Polarised light micrograph of a Suctoria sp. ciliate protozoan (centre) on Cladophora sp. green algae. Suctoria obtain food through specialised suctorial tentacles that allow them to fasten themselves to their prey. While fully developed Suctoria do not have cilia, they are classified as ciliates because of the presence of cilia during the larval stage. Magnification: x400 when printed 10 centimetres wide.