The phylum Ciliophora, includes about 8000 known species of some of the most complex single-celled organisms ever. These complex unicellular organisms are covered with relatively short, dense hairlike structures, called Cilia, used for locomotion.
Most ciliates are free-living organisms, but many parasitic forms exist. Free-living ciliates can be found almost anywhere there is water, and they generally feed on bacteria, but their large cell sizes allow them to exploit more prey types such as algae, flagellates, and other ciliates.
