Deep-water organisms depend on thesurface not only for food, but also for oxy-gen (O 2). If the ocean were stagnant, theoxygen below the surface would bequickly used up by respiration and animallife would be impossible. Fortunately in regulating the earth’s climate. Further-more, it constantly replenishes the supply of oxygen to the deep sea. Oxygen may become depleted in some places, but by and large the ocean depths have plenty of oxygen to support life.