Unlike other members of the phylum Chordata, amphioxi are capable of phagocytosis, a digestive process in which food particles are consumed by individual cells. The oral cavity of the small animals is lined with cirri, which act as a food filtration system. Cilia fringing the gill slits direct water through the small mouth opening of the organism into the pharynx. The mucous membrane of the gill basket catches food particles in the water and passes them to the gut where they are exposed to various enzymes that initiate digestion.