By Billie Rubin, Hemoglobin’s Catabolic Cousin, reporting from the labs of Stanford Blood Center
The next time you hear somebody say they have “blue blood” in their ancestry & are trying to tell you that they are of royal blood lineage think “molluscs.” Because they must have a high class horse-shoe crab, clam, squid, or octopi in their family tree.
Molluscs are the true blue bloods of the world. Their blood is truly blue when they bleed because instead of hemoglobin, they have a copper-containing protein called hemocyanin which turns dark blue when exposed to oxygen. So, try to be understanding of your blue-blooded friend: their great, great grand-daddy was a royal horse-shoe crab, and they are proud of it.