Why is Blood Red in Colour?

Haemoglobin protein is made up subunits called hemes, what give blood its red color.

Why is blood red in colour?

Our blood mainly consists of. A liquid called plasma, red blood cells, white blood cells and platelets. However, the colour of our blood is basically because of red blood cells. Each of the red blood cells contains haemoglobin. Haemoglobin is an iron-rich protein. When haemoglobin binds with oxygen. The interaction between them gives our blood its red colour. Moreover, like human beings, not all animals have red colour blood. This is because of the blood of some animals. Such as octopuses, spiders, etc. has hemocyanin instead of hemoglobin. Hemocyanin is a copper-containing protein. When hemocyanin binds with oxygen, their interaction gives the blood a blue colour. The blood of some lizards has biliverdin instead of hemoglobin. Which give their blood a green colour.