Cephalopod circulatory system

Cephalopods are related to their life habits such as rapid movement and predation. They have a closed-tube circulation system and are the only type of mollusks with closed-tube circulation. There is one ventricle and 2-4 atrial appendages in the pericardial cavity. The number of atrial appendages is the same as the number of gills and kidneys. Therefore, Nautilus has 4 atrial appendages and other species have 2 atrial appendages. 

The anterior aorta and posterior aorta (posterior aorta) pass from the ventricle forward and backward respectively. They run forward and backward, and branch, enter the tissue cells with capillaries, and then the blood from the head and the front of the body gathers into the anterior vena, and the end is divided into two branches, passing through the kidney capsule. The blood vessels of the back of the body, mantle and internal organs converge to form the posterior vena, which is also divided into two ends, and merges with the two branches of the anterior aorta to enter the gill core. 

The gill core is also muscular, and its contraction can be Increase the blood pressure into the gill blood vessels. There are also capillaries in the gill filaments. After the blood completes the gas exchange, it flows out of the gill vessels and then flows into the auricles and ventricles; thus completing blood circulation. The blood of cephalopods contains hemocyanin.