Physiology of Finfish and Shellfish (2+1)

2.2.15. Working of the teleostean heart

Rhythmic contraction and ejection (systolic) and expansion or relaxation and filling (diastolic) of the chambers, 1 after another forces the blood forward into the ventral aorta. Any backward flow of blood under pressure is prevented by the semi lunar valves, which become full of blood and bulge out, adhering with each other so as to close the aperture. From the ventral aorta, the blood goes to the gills through the afferent branchial vessels for aeration.