Ecological Pyramids

An ecological pyramid is a graphical way of representing the relationship between the successive trophic levels of a food chain in an ecosystem, in terms of the number of organisms present, the total biomass present, or the total energy present at each level. The concept was introduced by the ecologist Charles Elton in 1927 and remains one of the simplest visual tools for comparing how a community's organisms, mass, or captured energy are distributed across the feeding hierarchy from producers up to top consumers.

In every ecological pyramid, by convention, the producers -- the first trophic level -- are represented at the broad base of the figure, and each successive trophic level above them is stacked in order, narrowing (in most, though not every, case) toward a much smaller apex occupied by the top or tertiary consumers. Three distinct kinds of ecological pyramid are studied, based on what quantity is being plotted at each trophic level: the pyramid of numbers, which plots the count of individual organisms present at each level; the pyramid of biomass, which plots the total standing mass of living material present at each level; and the pyramid of energy, which plots the total amount of energy present or flowing through each level over a given time period. …