Why a lobster blood is colorless but when exposed to oxygen it turns blue?

Question: Why a lobster blood is colorless but when exposed to oxygen it turns blue?
- Keywords:
  blood,
  lobster
Asked by 746ylwj1734 to Byron, David, Esther, Jacquie on 15 Jul 2017.
- Byron Bitanihirwe answered on 15 Jul 2017:
  
  The bluish tint of a lobster’s blood is due to the presence of copper found in the blue haemocyanin molecule in their blood. Hemocyanins are not bound to blood cells but are instead suspended directly in the hemolymph.
  Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form.