Why do octopuses have three hearts?

Octopuses have three hearts to support their active lifestyle and oxygen demands. Two branchial hearts pump blood through the gills to oxygenate it, while the central systemic heart circulates the oxygen-rich blood to the rest of the body. Interestingly, the systemic heart stops beating when the octopus swims, making them tire quickly during sustained movement. This unique circulatory system helps them thrive in their aquatic environment, where efficient oxygen delivery is crucial for survival.