This bending forces the external liquid over the cell surface, which clears stale liquid and debris away from the cell, brings new food and oxygen to the cell, or moves the cell into a new environment.
Cilia are present on single-celled organisms such as paramecium, a tiny, free-living protist that can be found in fresh water ponds. Usually about 2-10 µm long and 0.5 µm wide, cilia cover the surface of the paramecium and move the organism through the water in search of food and away from danger.
Cilia are also found, in modified form, in tissues such as the kidney and pituitary gland.
Flagella are often longer than cilia, about 50-100 µm in length, and there are rarely more than two per cell. they provide movement by an undulatory motion and are typically found as the motile organelle of animal sperm and some plant male gametes.