Why Do Cuttlefish Have Blue Blood?

💡 The Answer

• Cuttlefish have blue blood due to a protein called hemocyanin. This protein contains copper instead of iron.
• Hemocyanin transports oxygen in their bloodstream. It functions similarly to hemoglobin in humans.
• The copper-based molecule gives their blood a blue color when oxygenated. This is a key difference from mammals.
• This adaptation works well in cold and low-oxygen environments. It helps them survive deep or challenging waters.