Stentor polymorphus, the green 'trumpet animalcule'. This species contains symbiotic algae of the genus Chlorella. Stentor is one of the largest ciliates, reaching 1 millimetre in length. They can just be seen with the naked eye. Often they use a holdfast to stay attached to a substrate but they can also be found swimming.

See another green species of Stentor.

Part of the Collection of the Ciliate Centre of the Micropolitan Museum © Wim van Egmond