Ecological pyramids are of three general types namely:
(i) Pyramid of numbers, showing number of individual organisms at each level
(ii) Pyramid of biomass, showing total dry weight and or suitable measures of total amount of living matter, and
(iii) Pyramid of energy, showing rate of energy flow and/or productivity at successive trophic levels. (always upright)
Of three types of ecological pyramids, energy pyramids give best picture of overall nature of ecosystem. Here number and weight of organisms at any level depend not on amount of fixed energy present at any one time in level just below but rar on rate at which food is being produced. In contrast with pyramids of numbers and biomass, which are pictures of standing situations like organisms present at any moment pyramid of energy is a picture of rates of passage of food, mass through food chain. In shape, it is always upright, as in most of cases re is always a gradual decrease in energy content at successive trophic levels from producers to various consumers.
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