Bee blood, called hymolymph, does not require hemoglobin to carry oxygen and so is not red or blue but almost colorless. It performs two main functions: serving as a medium for the distribution of pressure and as a vehicle in which chemical substances, nutrients and waste are transported. Hymolymph is pumped through a muscular elongated heart which stretches from the tip of the abdomen to just behind the brain. The heart has four chambers and five pair of openings, called ostia. Pushed forward from the abdomen into the thorax where it flows into the legs and wings, and on into the head where it bathes the brain, the hymolymph then begins its return journey back through the open cavities of the body where it deposits wastes and picks up new compounds, is taken up by the ostia again and recirculated.