Cilia, << SIHL ee uh, >> are tiny, hairlike structures that project from certain kinds of cells. Cilia are slender and move constantly. They can be seen only under a microscope. In many animals, cilia are found in cells of the membranes of the nose, the ear, and the tubes leading toward the lungs. The wavy motion of the cilia in these organs pushes out dust, bacteria, and mucus, and keeps the passages clean. In a clam, cilia-containing cells fan water containing food and oxygen into the animal. Many one-celled organisms have cilia that serve as sense organs and provide a means of locomotion. See also Protozoan (Ciliates) .
