[2] Usually forming a pair of lateral structures, oesophageal pouches take various forms, but usually account for a fair portion of the anterior volume of the creeping molluscs and scaphopods.
[3][4][5][6][7] There is a single pouch ventral to the rear of the radula in some nudibranch sea slugs.
[6] The pouches are lined with ciliated secretory cells.
[8] The pouches contain digestive enzymes that break down starch and other polysaccharides,[1] and also extrude mucus.
[6] The features are considered ancestral to molluscs[2] and are present in monoplacophorans,[9] but have been secondarily lost in the Heterobranchia.