Vorticella ciliates. Light microscope differential interference contrast (DIC) footage of a group of Vorticella peritrich ciliates attached to algae. These sessile microscopic organisms are filter feeders, with rows of cilia and an undulating membrane creating a current of water which directs food particles towards the buccal cavity (mouth opening). Attached with a contractile stalk to their substrate, they can react very fast to any disturbance. Several such contractions are seen in this clip. Magnification: x390 at 10 centimetres across.