Branchial heart
![Ventral view of the viscera of Chtenopteryx sicula, showing the presence of the branchial hearts.](/Images/godic/202502/02/Chtenopteryx_sicula2_-_from_Commons1506.jpg")
Branchial hearts are myogenic accessory pumps found in coleoid cephalopods that supplement the action of the main, systemic heart. Each consists of a single chamber and they are always paired, being located at the base of the gills. They pump blood through the gills via the afferent branchial veins. Since they only circulate venous blood, branchial hearts function under predominantly anaerobic conditions. Branchial hearts also appear to be involved in hemocyanin synthesis.