Circulatory system of gastropods

As in other molluscs, the circulatory system of gastropods is open, with the fluid, or haemolymph, flowing through sinuses and bathing the tissues directly.

In the great majority of species, it has two chambers; an auricle, which receives haemolymph from the gill or lung, and a ventricle, which pumps it into the aorta.

De-oxygenated haemolymph drains into a large venous sinus within the head and foot, which contains the nephridium, an excretory organ with a function similar to that of the vertebrate kidney.

In some genera, such as the large marine snail Busycon, the main anterior artery (which supplies the head and foot) includes an enlarged muscular region.

Regardless of whether they employ haemocyanin or haemoglobin, the pigments are dissolved directly in the serum, with no equivalent of the red blood cells found in mammals.