Why Do Octopuses Have Three Hearts?

💡 The Answer

• Two branchial hearts pump blood to the gills for oxygenation
• One systemic heart pumps oxygenated blood to the rest of the body
• Octopus blood uses copper-based hemocyanin instead of iron-based hemoglobin
• This makes their blood blue and less efficient at carrying oxygen
• The extra hearts compensate for the inefficient oxygen transport
• When an octopus swims, the systemic heart stops beating, which is why they prefer crawling