The cephalopod circulatory system is highly vascular, and consists of arteries, veins, and capillaries. They have three different hearts contained in a closed off- circulatory system. No other mollusk has these dynamics, so the cuttlefish’s system is quite unique. Two of the hearts in the system are called brachial hearts, and are responsible for pushing blood through the gills for gas exchange. They pump blood in tandem on either side of the mantle cavity. The third heart is the systemic heart, and it is what receives both oxygenated, and deoxygenated blood, similar to human’s hearts. 

 

Nerves run throughout the circulatory system , and there is a cluster that seems to serve as a “pacemaker” mechanism called the cardiac ganglion. From the gills, afferent brachial nerves are the small vessels that run through the gills and proximal to the lamellae, and are what push freshly oxygenated blood into large veins that then flow to the hearts of the cuttlefish. (yes, that was plural). 

 

 

 

 

 

 

 

 

 

 

 

 

Human hearts contain large veins, two of which we refer to as the inferior, and superior vena cava. Cephalopods also have two large veins that pump blood to the brachial hearts, and because the two hearts are situated on either side of the mantle cavity, these veins are called the anterior and lateral vena cava. 

 

Once blood has passed through the branchial hearts, it then flows into the systemic heart - which is responsible for maneuvering the blood to other essential organs and tissues. The cephalic artery is responsible for this mechanism. Similar to human anatomy, arteries flow blood away from the heart - the same concept is present in cuttlefish. Veins bring oxygenated and deoxygenated blood to the hearts, and arteries carry oxygenated blood away from the heart, and into key organs.