Like most mollusks, the clam has an open circulatory system. Similar to other organisms with an open circulatory system, clams also have a pericardium in which blood pools as it is awaiting to brought into the actual heart. Blood is pumped from the heart into the aorta, where it goes to various parts of the clam's body such as the kidneys and gills. After passing over these two organs, the blood is reoxygenated and nutrient-rich and is directed back towards the heart. Once it gets to heart the oxygen and nutrient-rich blood is pump throughout the clam's body once again, and the process is restarted.