Unlike most animals that have a single heart, octopuses are equipped with three distinct hearts, each serving a unique function.
Two of an octopus's hearts pump blood to its gills, while the third pumps it to the rest of the body. Interestingly, when an octopus swims, the heart that delivers blood to the rest of the body actually stops beating, which makes swimming a tiring activity for them. This incredible adaptation highlights how uniquely octopuses are built for their environments.