Question

Which of the following ecological pyramids can be inverted?
a. Pyramid of energy
b. Pyramid of number
c. Pyramid of biomass

• A. Only (a) and (b)
• B. Only (b)
• C. Only (b) and (c)
• D. All (a), (b), and (c)

Answer 1

Answer: (C)

The pyramid of energy is always upright because the flow of energy is unidirectional from producer to consumer level. The energy content is maximum in producers. The energy decreases at each trophic level of the food chain, as part of the energy is lost as heat, and the major part of the energy is liberated during respiration for use in various activities.
Only 10 % of the energy of the previous trophic level is received by the next trophic level, as proposed by the 10 percent law of Lindeman (1942).
A pyramid of biomass is a graphical representation of biomass present per unit area at different trophic levels. Tree and grassland ecosystems are upright as the total biomass of plants (producers) in a specific area is more than that of herbivores (primary consumers) and it gradually decreases at each successive trophic level. It is the least in top carnivores.
Marine biomass pyramid is often inverted as the producers are very small and have limited mass.
A pyramid of numbers is a graphical representation of the number of individuals present per unit area at different trophic levels.
In, most ecosystems, the number of producers is maximum. Producers thus can support fewer herbivores and herbivores can support still fewer carnivores and so on. Thus the number of top carnivores is too small to support any other trophic level and does not act as prey to any other organism.
In the parasitic food chain, at each successive trophic level, the number of organisms is higher than in the preceding one, and the size decreases gradually at a successive level. Thus, the shape of the pyramid may be inverted.