Portrait of Actinobolina, a haptorid ciliate with retractile tentacles spaced at intervals along longitudinal uniform ciliary rows. Oval in shape with small apical anterior oral aperture. Tentacles retract during swimming and elongate dramatically when resting. Each tentacle bears a long cylindrical toxicyst at its end. Tentacles are not knobbed as in many Suctoria. Prey are paralyzed by toxicysts then manoeuvered to the oral aperture for ingestion. Several species some with Zoochlorellae. This individual has just come to rest with tentacles beginning to extend. From freshwater pond near Boise, Idaho. Phase contrast.
