TODAY'S SCIENCE TRIVIA: Invertebrates such as spiders have an open circulatory system, which means that the oxygen-carrying fluid running through it is in contact with its muscles and its other internal fluids. This blood analogue is called hemolymph, and instead of the iron-carrying hemogoblin that we find in our blood, it has hemocyanin, a copper-based protein that, when oxygenated, turns bluish-green in color.
