Because of the dependence on sur-face production for food, life is much lessabundant below the photic zone than inthe sunlit surface layer. Most food parti-cles get eaten before they sink into deeper water. With food in short supply, pelagicorganisms become more and more scarceat greater depths. There are typically 5 or10 times fewer organisms at 500 m(1,600 ft), for example, than there are atthe surface, and perhaps 10 times feweragain at 4,000 m (13,000 ft).