Why is Blood Red?

The video explores the different colors of blood in various animals, explaining the molecules responsible for these colors. Horseshoe crabs have blue blood due to hemocyanin, which contains copper. Deep sea worms have pink blood because of the molecule hemorrhythrin. Human blood is red due to hemoglobin, which contains iron. Hemoglobin is the most efficient oxygen carrier, making red the most common blood color in the animal kingdom.

How does hemoglobin change color when oxygen is bound and released?

Why is red the most common blood color pigment in the animal kingdom?