“Octopuses have three hearts”

The idea of an animal possessing multiple hearts often sounds like something from science fiction, leading many to question its truth. However, in the case of the octopus, this surprising biological detail is entirely accurate. These intelligent cephalopods are indeed equipped with three hearts, a unique adaptation that is crucial for their survival and active lifestyle in the ocean.

Scientifically, an octopus's circulatory system features two branchial hearts and one systemic heart. The two branchial hearts are strategically located near the gills, where their primary role is to pump deoxygenated blood through the gills to pick up oxygen. Once oxygenated, this blood then flows to the single, larger systemic heart, which is responsible for circulating the oxygen-rich blood throughout the rest of the octopus's body, including its arms and organs. This complex system is necessitated by their copper-based blood, which uses hemocyanin instead of the iron-based hemoglobin found in human blood. Hemocyanin is less efficient at transporting oxygen, making the blood thicker and requiring more pumping power to ensure adequate oxygen delivery, hence the need for multiple hearts. This copper content also gives their blood a distinctive blue color when oxygenated.

The reason this fact might seem like a myth to many stems from our familiarity with most vertebrates, which typically have a single heart. The octopus's distinct physiology, evolved to thrive in its marine environment, stands in stark contrast. Interestingly, the systemic heart even stops beating when the octopus swims, which is why these creatures often prefer to crawl across the seafloor rather than swim for extended periods, as swimming can be quite exhausting for them. This remarkable adaptation highlights the diverse and often surprising ways life has evolved to meet environmental challenges.