 The digestive tract of typical bivalves consists of an oesophagus , stomach , and intestine . A number of digestive glands open into the stomach , often via a pair of diverticula ; these secrete enzymes to digest food in the stomach , but also include cells that phagocytose food particles , and digest them intracellularly . In filter @-@ feeding bivalves , an elongated rod of solidified mucus referred to as the " crystalline style " projects into the stomach from an associated sac . Cilia in the sac cause the style to rotate , winding in a stream of food @-@ containing mucus from the mouth , and churning the stomach contents . This constant motion propels food particles into a sorting region at the rear of the stomach , which distributes smaller particles into the digestive glands , and heavier particles into the intestine . Waste material is consolidated in the rectum and voided as pellets into the exhalent water stream through an anal pore . Feeding and digestion are synchronized with diurnal and tidal cycles . 
