How does the spiral valve in a lungfish heart help direct blood flow?

In the lungfish heart, the spiral valve is a complex system of valves arranged in a spiral pattern within the large conus arteriosus.1

This structure functions to direct blood flow by maintaining the separation of oxygenated and deoxygenated blood as it exits the heart. Specifically, the spiral valve ensures that:1

• Oxygenated blood from the left side of the ventricle is directed into the ventral division of the ventral aorta, where it passes to the anterior arterial arches to supply the head.1
• Deoxygenated blood from the right side of the ventricle is directed into the two most posterior arterial arches, which carry the blood primarily to the lungs for oxygenation.1

By facilitating this targeted distribution, the spiral valve allows lungfish to effectively manage blood flow between their gills and lungs.1