Choanocyte

Choanocyte (collar cell) - a flagellated cell that lines the interior of the central cavity (spongocoel) of a sponge. The choanocyte is ovoid with one end adjacent to the mesenchyme while the other end protrudes in the lobby and carries a flagellum surrounded by a collar basal contractile. Choanocytes have a tubular collar with an extended flagellum or undulipodia that faces the spongocoel and creates currents that force water into the interstices of the sponge. Suspended food particles, such as plankton, are trapped by the choanocytes and passed to an amoebocyte that carries the food to other cells.