Octopuses Have Three Hearts
Learn why octopuses have three hearts and why they prefer crawling to swimming.
Octopuses possess three hearts, each serving a specific purpose. Two of the hearts, called branchial hearts, pump blood to the gills where it picks up oxygen. The third heart, the systemic heart, then pumps the oxygenated blood to the rest of the body.
Interestingly, when an octopus swims, the systemic heart stops beating, which is why these creatures prefer to crawl rather than swim—it's less exhausting for them. Additionally, octopus blood is blue because it contains copper-based hemocyanin instead of iron-based hemoglobin like humans.