Ciliates are a large, varied group of protists named for their use of cilia to move and feed. The cilia may completely cover the cell surface or may be clustered in a few rows or tufts. In certain species, rows of tightly packed cilia function collectively in locomotion. Other ciliates scurry about on leg-like structures constructed from many cilia bonded together. A distinctive feature of ciliates is the presence of two types of nuclei: tiny micronuclei and large macronuclei.