The blood, or haemolymph of a bee carries no oxygen, (that is the job of the
tracheal system
) so does not contain the red pigment haemoglobin and as a result is a pale straw or amber colour. The blood carries nutrients to the tissue and organs of the bee and the waste products from metabolism to the excretion organs, the Malpighian tubules, for elimination. The bee’s blood also contains cells for destroying bacteria, dealing with foreign bodies and other toxic substances and also wound healing.
Unlike larger animals the bee’s blood is not contained within tubes but simply fills all spaces within its body, thereby surrounding all of its organs. This is called an open circulatory system, unlike our own which is a closed circulatory system. Blood circulation in a bee is achieved through a simple heart, which is an elongated organ lying just under the roof of the abdomen. It has muscular walls and has five pairs of openings with one-way valves which allow blood to enter the heart when it dilates. When the heart contracts, the valves close and the blood is forced forwards into the aorta which extends through the thorax and into the head where it ends just behind the brain.
It is worth noting that the only blood vessels to be found in a bee are at the base of each antenna, which force the blood to circulate through them, highlighting the importance of the antennae to a bee.
The bee’s heart pushes the blood forward into the brain until pressure increases forcing it back through the body cavity and to all the organs and tissues. On its way from the head, the blood passes back through the thorax, nourishing the flight muscles, then into the abdominal cavity where more nourishment is picked up from the digestive system before it is drawn back into the heart again.
photo courtesy of infovisual.info
