How does the circulation system in small insects works ?
Insects have what is called an ‘open’ circulatory system. This means that their blood does not flow through arteries, capillaries and veins, but rather it bathes the tissues and organs directly (sort of sloshes around inside their body). To make sure that the blood circulates the body cavity (or haemocoel as it is called) is divided up into internal spaces or ‘sinuses’, rather like the inside of a house has rooms. The blood flows from the head end backwards through these sinuses. Keeping the blood flowing is the heart (or rather hearts). This consists of a tube running almost the length of the insect’s body. Along this tube are contractile (squeezing) sections with valves, that push the blood towards the head end. Blood can enter this system of hearts from the rear end of the tube or from the sides through small holes. This open system is rather inefficient so is only found in small organisms like insects. Open circulatory systems are not involved in transport of respiratory gases. Tha
