There are four gills, two on each side. A complex arrangement of cilia on the surface of the filaments pumps water through the ostia, and captures small particles which are suspended in the water. These particles are then bound up in mucus and transferred toward the mouth by other cilia which are located at the margins of the gill. The current of water generated by the cilia enters the mantle cavity on the side facing the gills, and passes out on the opposite side. Feeding Phytoplankton, and other particles, captured on the gills are transferred to the labial palp located at the forward end of the gills, where the particles are sorted.
Food is directed toward the mouth.
Digestion starts in the stomach which is located in the upper part of the animal, close to the ligament. The crystalline style, an organ only found in molluscs, rotates inside the stomach, grinding the food and mixing it with digestive enzymes. Small particles are passed to the digestive gland which is visible in the opened animal as a brownish green mass surrounding the stomach, where digestion and assimilation continue. Waste material is passed along the intestine and ejected as feces into the exhalant current. Reproduction The gonad, or roe, is a crescent shaped mass of tissue partially surrounding the adductor.