Which animal has three hearts and blue blood?
An octopus has three hearts and blue blood. Two hearts pump blood toward the gills, where oxygen is absorbed, while the third circulates oxygenated blood to the rest of the body. Its blood appears blue because it contains hemocyanin, a copper-based protein that carries oxygen. This differs from the iron-based haemoglobin found in humans and many other animals. Hemocyanin works effectively in the cold, low-oxygen environments inhabited by numerous octopus species. Octopuses are also known for their intelligence, camouflage abilities and capacity to squeeze through remarkably small openings because they have no bones apart from their beak. Their nervous systems are unusual, with a large proportion of their neurons located in their arms, allowing complex movements and sensory responses.
