The natural diets have been investigated in only in a few species, and in these most of the food seems to consist of invertebrate larvae, microscopic animals, and protozoans. As is common in so many filter-feeding organisms, they utilize a combination of cilia and mucus to assist in either food capture or movement of the food to the mouth. Mucus is secreted by gland cells, and cilia are used to move this mucus. Chemically mucuses are called glycoproteins, or chemical combinations of sugars and proteins. Generally mucuses are sticky and viscous, although the latter property can often be varied by varying the ph of the medium.
Cilia are small, undulating processes located on the surfaces of cells.
Although they are often called hair-like, they are in point of fact, many thousands of times smaller than a human hair. Their motion results from the movement of slender protein fibrils located in them. In feather stars and many other ciliary-mucous filter feeding organisms, cilia can be found lining depressions of the body called food grooves. Mucus is secreted by the glandular cells lining the food grooves and moves in flowing stream toward the mouth, with the movement of the mucus due directly to the underlying cilia. It subdivides and continues out into the lateral small projections off the main arm and consists of a mucous-filled ciliated food groove which connects all the way to from the finest arm branch to the mouth on the upper surface of the body.