The Science Behind Blue Blood: Creatures That Use Copper Instead Of Iron

Introduction To Blood And Oxygen Transport: Blood is essential for carrying oxygen throughout the body, but not all creatures use the same system. Humans and most animals rely on hemoglobin, an iron-based protein that turns blood red when it binds with oxygen. However, some creatures have taken a different evolutionary path, using hemocyanin, a copper-based molecule, that gives their blood a distinct blue color.