The primary respiratory pigment in vertebrates is hemoglobin. Hemoglobin is found in red blood cells and is crucial for transporting oxygen from the lungs to the tissues while carrying carbon dioxide back to the lungs for exhalation. This protein binds to oxygen molecules, enhancing oxygen solubility in blood. The efficiency of hemoglobin is vital for maintaining cellular metabolism and overall health in vertebrates. Variations of this pigment exist across different species, allowing them to adapt to specific environments and oxygen levels.