the oxygen-carrying (colored) substances in blood and tissues (hemoglobin, myoglobin, hemocyanin, etc.).
res·pi·ra·to·ry pig·ments
(res'pir-ă-tōr-ē pig'mĕnts) The oxygen-carrying (colored) substances in blood and tissues (e.g., hemoglobin, myoglobin, hemocyanin). ThesaurusSeepigment