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Naveen Kumar

Ecological Pyramid

An Ecological Pyramid is the graphical representation of trophic levels in terms of Biomass, Energy concentrated at a particular trophic level, Number of Organisms, etc. When the organisms are plotted in terms of energy, Biomass, and Number associated at trophic levels, they assume the Pyramidical shape known as the Ecological Pyramid. They are also known as Eltonian Pyramid, named after Charles Elton who developed the concept of Ecological Pyramid. The horizontal bars in the pyramid signify the number of Trophic levels.


Types of Ecological Pyramid 

  • Pyramid of numbers 

  • Pyramid of Biomass 

  • Pyramid of Energy 


Pyramid of Numbers

  • The pyramid of the number shows the presence of the total no. of organisms of different species at each Trophic level. 

  • This type of Pyramid shows a relationship between the number of Primary producers, primary consumers, secondary consumers, tertiary and Quaternary consumers, etc. 

  • Depending upon the size and Biomass of the ecosystem the Pyramid of Numbers is of three types

  • Upright

  • Partially Upright 

  • Inverted. 

  • Since it is not possible all the time to count all the organisms, thus the pyramid of numbers does not define the trophic structure of an ecosystem. Also, it does not take into account the variation in the size of organisms present at each trophic level. 


  1. Upright Pyramid of Numbers (Grassland and Aquatic (Pond) Ecosystem)

  • The number of organisms successively decreases as we progress from lower to higher trophic levels (i.e. from producer to the consumers). 

  • In the grassland ecosystem grasses occupy the lowest trophic level, and grasshoppers are the primary consumers which are less in numbers. Rats are the secondary consumer whose number is even lesser than the grasshopper and the next higher trophic level is a tertiary consumer (snake) which feeds upon rats. The next higher trophic level is occupied by Hawks in the grassland ecosystem which is even lesser in number compared to snakes. Thus, with each successive level, the no. of organisms decreases making the shape of the Pyramid upright. 

  • In the same manner in the Pond ecosystem, the number of organisms decreases with each successive trophic level. 

  • The lowest trophic level is occupied by the snails then the next levels are followed by the following organisms: 

  • Smaller fishes (Lesser in no compared to Snails), 

  • Bigger Fishes (Primary Carnivore), 

  • Crane (Secondary Carnivore; lesser in number compared to bigger fishes). 


  1. Partially Upright Pyramid of numbers

  • The forest ecosystem is an example of a Partially upright ecosystem since fewer producers support more primary consumers (e.g. a single tree is capable of supporting a large no of Primary consumers) but afterward, the Pyramid attains the normal shape since there are fewer secondary and tertiary consumers. 


  1. Inverted Pyramid of numbers

  • In the inverted pyramid of numbers, the organisms that are dependent on lower trophic level grows closer to the apex as in the case of the Parasitic Food Chain. 

  • E.g. In this food chain primary producer is a large tree that supports a large no. of parasites or hyper-parasites as primary and secondary consumers. Thus the resultant shape of the pyramid is inverted. 

Ecological Pyramid

Pyramid of Biomass

  • Pyramid of Biomass includes the total weight of the organic matter i.e. Biomass, at each trophic level. 

  • The Pyramid of Numbers does not give any idea of weight since it does not take into account the varying shapes and sizes of the organisms, so to fulfill the shortcoming of the ‘Pyramid of Numbers’ the ‘Pyramid of Biomass’ has been introduced. 

  • Pyramid of Biomass measures the total biomass in grams per meter^2 or Calories per meter^2 and this also signifies the amount of matter lost between successive trophic levels. 

  • Pyramid of Biomass doesn’t give any idea about the rate of ecological/ ecosystem productivity. 


  1. Upright Pyramid of Biomass

  • In the upright pyramid, the total weight of the producer is larger than the total weight of the consumers. 

  • Example- In the case of a forest ecosystem, the tree that is the producer/autotroph has larger biomass compared to primary or secondary consumers like Birds, insects, etc. Thus, the attained shape is upright. 


  1. Inverted Pyramid of Biomass

  • In the case of the inverted pyramid, the total weight of the producer is smaller than the total weight of the primary or secondary consumers. 

  • Example- In the case of an aquatic ecosystem, phytoplankton which supports smaller fishes have lesser biomass, while at the next trophic level, the herbivore fishes have lesser biomass than the carnivore fishes. Thus, we attain an inverted shaped pyramid. 

Pyramid of Biomass

Pyramid of Energy

  • To find an idea about ecological productivity Charles Elton, developed a Pyramid of Energy. 

  • The pyramid of energy represents the total amount of energy present at each trophic level per unit area per unit of time and energy is generally expressed in terms of Kcal/m2/day or Kcal/m2/year. 

  • The pyramid of energy is always upright since the total energy available for utilization for the successive trophic level is less than the energy available for the previous trophic level. Successive reduction in energy is due to the use of energy for activities like respiration or simply due to heat loss. 

  • The energy pyramid helps in the comparative study of the productivity of a different ecosystem. 

  • The energy pyramid also helps to explain the concept of Biological magnification in which the toxic substances are deposited more at successively higher trophic levels. 

Pyramid of Energy

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