A “bass pond” contains far fewer bass than small sunfish on which the bass prey. Likewise, fewer sunfish swim in a pond than the many insects, small crustaceans, and snails eaten by sunfish. These very small prey in turn are fewer – both in number and total weight – than their food source consisting of the myriads of microscopic plants drifting in the water and growing on the bottom. This fundamental pattern of nature where a few predators are supported by large numbers of those on which they feed repeats itself everywhere on land and beneath the waves. In the 1920s, British ecologist Charles Elton named this pattern the “pyramid of numbers.” Today ecologists refer to the concept as a “trophic pyramid” or reverently as an “Eltonian pyramid.”
