Protists are large group of organisms which includes unicellular and multicellular species. Currently there are disputes in the taxonomy or classification of species since there are issues regarding that.
One of classification of protist is the ciliates (phylum ciliophora). They are one of the most studied protists today. They are under the domain eukaryota kingdom Chromalveolata which are characterized by hair-like organelles called cilia. They used this in order to gather food and for locomotion.
The most common ciliates known is the paramecium. They used their cilia in order to gather food and water by sweeping it into the oral groove until it reaches the mouth opening.