A ciliate is any one of the approximately 8,000 species of the phylum Ciliophora characterized by hair-like cilia used for locomotion and food collecting. Ciliates are the largest and most complex of the Protozoa. Subclasses include the Holotrichs, with cilia over the entire body (Paramecium); Spirotrichs, with fused cilia around the mouth (Stentor); and Peritrichs, with cilia around the mouth and possessing a stalk for attachment (Vorticella). Ciliates are found in both aquatic and terrestrial habitats and many are carnivorous, They have two nuclei – a macronucleus and a micronucleus – and a variety of organelles such as a cystome (mouth).