Why do different animals have different blood colors? If red blood is caused by Red Blood Cells, do crabs have “Blue Blood Cells”?
In: Biology
The red color of red blood cells is due to hemoglobin which is the molecule they use to carry oxygen.
Horseshoe crab’s equivalent of our red blood cells use a different compound to carry oxygen, which is blue instead of red (because contains copper instead of iron).
Horseshoe crabs use hemocyanin the key atoms are copper atoms not iron like in Haemoglobin and myoglobin in most red blooded mammals. https://youtu.be/t6kQhilO04c
Different color because they evolved different molecules for carrying oxygen. Our blood is red because we evolved hemoglobin which is a red color, and we store it in red blood cells because it’s a small molecule that would clog our kidneys if it was just mixed in our blood.
Crabs evolved hemocyanin instead, it is blue. Hemocyanin is much bigger than hemoglobin so they don’t have blue blood cells, it’s just mixed in with their blood without doing any harm.
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