Why do large organisms need specialised exchange systems and what are the features of an efficient exchange surface?

Large organisms have-High metabolic activity (used in movement, respiration, reproduction etc)Large distance between cells and the incoming oxygen that they requireA very small surface area to volume ratio meaning substances cannot reach the target areas of the body through simple diffusionEffective exchange surfaces typically consist of-Thin walls to make the diffusion pathway shorter (such as thin epithelial walls in alveoli)A good blood supply or ventilation in order to maintain a concentration gradientMoist surfaces allow gases to dissolve Large surface area for maximising the rate of diffusion