Coral Reef Fact:
Common cuttlefish (Sepia officinalis)
The cuttlefish has three hearts, with two pumping blood to its large gills and one circulating the oxygenated blood to the rest of its body. The blood itself is blue-green in color because it possesses hemocyanin, a copper-containing protein typical in cephalopods—cuttlefish, octopuses, and squids.
For more info http://www.pbs.org/wgbh/nova/camo/