Horseshoe crabs, lobsters and most molluscs have blue blood. Human blood gets its red colour because of haemoglobin where the iron atoms bind to oxygen to give the red colour. Crustaceans or crabs and lobsters get the blue colour from the pigment called ‘hemocyanin’ that carries oxygen in their blood. The copper atoms absorb oxygen and result in a blue-green colour when it oxidizes. The horseshoe crab’s blood is very valuable in current times. The presence of a special clotting agent in it allows scientists to detect bacterial endotoxins in medical applications like vaccines.
Why do horseshoe crabs have blue blood?
