The Eight-limbed Mollusk
Octopuses are soft-bodied cephalopods of the order Octopoda. Notably intelligent, over two thirds of their brain is stored in their eight arms. Octopuses inhabit coral reefs, pelagic waters, and the seabed. Most species grow rapidly, mature early, and are short-lived.
Octopuses are famous for rapidly changing color to blend in with their surroundings. Octopuses can shift hues because they have chromatophores — tiny, color-changing organs that are dotted throughout an octopus's skin.
An octopus has three hearts that pump blue blood through their veins. The blue blood is because the protein, haemocyanin, which carries oxygen around the octopus's body, contains copper rather than iron like we have in our own haemoglobin.