Choanocytes (also known as "collar cells") are
cells that line the interior of
asconoid, syconoid and leuconoid body type
sponges that contain a central
flagellum, or
undulipodia, surrounded by a collar of
microvilli which are connected by a thin membrane. They make up
Choanoderm, a type of cell layer found in
sponges. The cell has the closest resemblance to the
choanoflagellates which are the closest related single celled protists to the animal kingdom (metazoans). The flagellae beat regularly, creating a water flow across the microvilli which can then
filter nutrients from the water taken from the collar of the sponge. Food particles are then
phagocytosed by the cell.
