An octopus has three hearts. Two of these are called branchial hearts, and they pump blood to the gills where it picks up oxygen. The third heart, known as the systemic heart, pumps the oxygenated blood to the rest of the body to supply energy to the organs and muscles, including the eight tentacles
. This three-heart system is related to the octopus's blue blood, which contains a copper-based protein called hemocyanin that transports oxygen less efficiently than the iron-based hemoglobin in red blood. The two branchial hearts ensure blood is pumped through the gills to oxygenate it, while the systemic heart circulates this oxygen-rich blood throughout the body
. Interestingly, when an octopus swims, the systemic heart temporarily stops beating, which causes the octopus to tire quickly
. In summary:
- 2 branchial hearts pump deoxygenated blood to the gills.
- 1 systemic heart pumps oxygenated blood to the body.
This unique circulatory system supports the octopus's active lifestyle and extensive nervous system
