Did You Know?

Source

National Geographic

Octopuses have three hearts

And blue blood. And nine brains, sort of.

Two of an octopus's hearts pump blood through its gills; the third circulates it through the body. Their blood is blue because it uses copper-based hemocyanin instead of iron-based hemoglobin — better suited to cold, low-oxygen ocean depths. Each of their eight arms contains a mini-brain that can act independently of the central one.