pyramid of numbers


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Fig. 263 Pyramid of numbers.

pyramid of numbers

a means of depicting TROPHIC LEVELS to illustrate the numbers of organisms at any one level. The broad base indicates the large numbers of PRODUCERS, the next (narrower) stage the numbers of PRIMARY CONSUMERS, a third stage (narrower still) of SECONDARY CONSUMERS and at the apex the top PREDATOR. It is better expressed in terms of biomass or energy (see ECOLOGICAL PYRAMID), as in some cases, such as parasites higher in the trophic levels than the host, greater numbers occur higher, and do not produce a pyramid when numbers only are considered. See Fig. 263 . and FOODCHAIN.