What is the circulatory system of gastropods?

The circulatory system of gastropods is open, with fluid, or hemolymphs, flowing directly through the sinuses of the tissue. Hemolymph usually contains hemocyanin and is blue in color. The heart is in front of the visceral mass. In the vast majority of species, it has two chambers: the atrium, which receives hemolymph from the gill or lung, and the ventricle, which supplies it to the aorta. However, some primitive gastropods have two gills, each supplying its own shell, so that their heart has three chambers.