Did You Know!
Blood Isn’t Always Red Across Nature—but Humans Have One of the Brightest Shades
Human blood looks bright red when oxygenated and dark red when deoxygenated because of iron in hemoglobin. But in other animals, it can be blue (octopuses, due to copper-based hemocyanin), green (worms with chlorocruorin), or even purple (certain sea creatures with hemerythrin). So while red blood seems “normal” to us, it’s just one version nature came up with.
