A terrestrial organism has the advantage of obtaining oxygen from the atmosphere where the oxygen concentration is about 21%, which is significantly higher than the concentration of dissolved oxygen in water (usually less than 1%). This means terrestrial organisms can efficiently extract oxygen from the air using lungs or similar respiratory organs without needing to breathe rapidly. In contrast, aquatic organisms rely on extracting oxygen dissolved in water, which is much lower in concentration, causing them to have a faster breathing rate and more energy-demanding adaptations like gills to meet their oxygen needs. Hence, terrestrial organisms get sufficient oxygen more easily and with less respiratory effort compared to aquatic organisms.