Cephalopods are the only mollusks to have a closed circulatory system. These animals can either haves branchial heart, better known as two gill hearts that move blood through the capillaries of the gills. They can also have a single systemic heart then pumps the oxygenated blood through the rest of the body. The cephalopods use hemocyanin, a copper-containing protein, rather than hemoglobin, to transport oxygen. As a result, their blood is colorless when deoxygenated and turns blue when exposed to air as opposed to humans who have red blood since we use hemoglobin. The two other hearts of this animal pump blood to the gills where it dumps the wast, deoxygenated blood, and picks up oxygen