Nancy and I rescued this small octopus on Ft. Myers Beach in Florida. What is unusual about the circulatory system of an octopus?
An octopus has three hearts. Two of them are attached to the gills, pumping blood to collect oxygen. The third heart pumps the oxygenated blood to the rest of the body. They also have blue blood. Instead of having hemoglobin, which is red due to iron to carry oxygen, an octopus has hemocyanin, which is blue due to copper. This one was very small, so it was easy to put it back into the water, but some species, like the Pacific Octopus, can grow up to 600 pounds.