The animal known to have three hearts is the octopus. As a cephalopod, octopuses have a unique circulatory system, comprising three hearts that serve different functions. Two of the hearts pump blood to the gills for oxygenation, while the third heart distributes the oxygen-rich blood to the rest of the body. This efficient system adapts well to their aquatic environment, allowing them to be agile hunters. Interestingly, when an octopus swims, the heart that delivers blood to the rest of the body temporarily stops, making their movement less efficient compared to when they crawl. The octopus’s remarkable anatomy highlights its evolutionary adaptations.