An octopus has three hearts. Importantly surpasses the blood through the
body. Others pushing it through their gills. Due to the fact that in
the plasma and erythrocytes present hemocyanin (in which the copper
replaces the iron) instead of hemoglobin, the blood of the animals blue.
An octopus has large eyes with rectangular pupils. The head of the
animal is well developed, has a cartilaginous skull.