Insects have open circulatory systems that directly bathe their organs with fluids. Considering that this form of circulatory system is less efficient than a closed system, how are insects able to maintain life processes at remarkably high metabolic rates?

The circulatory fluid is known as hemolymph. When the heart pumps hemolymph through vessels into sinuses (various fluid-filled and air-filled spaces) where materials are exchanged between the hemolymph and cells. Hemolymph returns to the through pores, which have valves that close whenever the heart contracts.