Which respiratory pigment is responsible for the transport of oxygen in the blood of arthropods and molluscs, imparting a blue color to their blood?

💡 Solution & Explanation

Hemocyanin is a copper-containing respiratory metalloprotein found freely dissolved in the hemolymph of many arthropods and molluscs, turning blue upon oxygenation. In contrast, hemoglobin is an iron-based pigment that appears red and is typical of vertebrates. Hemerythrin is an iron-bearing protein found in marine invertebrates that turns violet-pink when oxygenated.