Alternative oxygen biochemistries for medicine

Animals use multiple fundamentally different chemistries to move oxygen — copper‑based hemocyanin (blue), iron‑based hemerythrin (purple), biliverdin‑rich blood (green), and even no hemoglobin (white) in some icefish. Those variants have distinct functional tradeoffs (cold performance, immune roles, transparency) that could inspire synthetic blood substitutes, cold‑adapted biomolecules, or new diagnostics. — Recognizing and studying non‑hemoglobin oxygen systems points to biomedical and biotech opportunities (synthetic transfusion products, novel enzymes) and raises conservation and biosecurity questions about exploiting unique biochemistry.