How do cilia create a feeding current in cephalochordates?

In cephalochordates, also known as lancelets, feeding currents are generated by the rhythmic beating of cilia located on the gill slits.12

These hairlike cellular extensions act to draw a continuous stream of water into the mouth and through the pharynx. As water passes through the gill basket, an endostyle secretes a sheet of mucus that traps suspended food particles. Cilia lining the pharynx then transport this food-rich mucus upward, where it is eventually moved to the intestine for digestion. This process allows the organism to effectively filter small particles from the water while preventing larger debris from entering, thanks to the grid-like structure of the buccal cirri surrounding the mouth.123