Ocean animals have developed various strategies for maximizing energy input from food. A. Large carnivores near the ocean surface feed mainly on organic matter left over after it passes through the filters of the filter-feeders. B. Even in deep ocean layers where prey is relatively hard to find, filter feeding is still the least energetically-demanding method of obtaining food. C. Animals in deeper water have evolved strategies and body structures that allow them to use as little energy as possible in obtaining food. D. Near the surface of the water, many animals obtain food by using specialized body parts to filter plankton from the water. E. Filter-feeding is more common in shallow water, where there is a higher concentration of organic matter than there is in deeper water. F. At deeper ocean levels plankton is relatively rare, requiring animals at those levels to actively search for their food sources.