Trophic levels in an ecosystem


Trophic levels depict the way energy, traits and biomass is getting transferred from one level to another. Not every organism can fit at the same level in a pyramid otherwise it causes an imbalance in the system. There must be a logical sequencing of different trophic levels. The sequence must be in such a way that, there should be more producers than the consumers, in other words, as we move up the ladder, there is a reduction in the number of organisms at each level. This will ensure there will be a balance between energy creation (biomass) and its destruction. The energy flow must be in a single direction, i,e from producers towards consumers(lower end of the pyramid to the higher end). As the chain progresses up, the amount of energy transfer, as well as the number of organisms decreases resulting in the reduction of the quantity of biomass at every successive level. Suppose assume that there is1000 kilograms of grass at a given time point, proportionately, the deer population shouldn't exceed 10. On the other hand,  the tiger population must only 1.  Trophic levels are diagrammatically illustrated in the form of pyramids. Some of the common ecosystems and their trophic levels are described below. 


Definition of trophic level 

A trophic level is a position in which a group of organisms within an ecosystem occupy a certain position. A trophic level is called so when different classes of organisms occupy different levels in a food chain (with few exceptions). Theoretically,  there are 4 trophic levels within a food chain. They are  

1. Level 1: Plants and algae make their own food and are called producers.

2. Level 2: Herbivores eat plants and are called primary consumers.

3. Level 3: Carnivores that eat herbivores are called secondary consumers.

4. Level 4: Carnivores that eat other carnivores are called tertiary consumers.


Tropic levels in an ecosystem

Trophic levels indicate the status and position of different species. Based on the trophic levels, species are arranged into Primary produces, primary consumers, secondary consumers and the tertiary consumers. As we move up the pyramid, the number of organisms decreases. 


Ecological pyramids 

An ecological pyramid, also called a trophic pyramid, energy pyramid, or simply a food pyramid. Different types of pyramids can be of aquatic ( pond, river, canal, ocean), terrestrial( desert, rain forest) or artificial. An ecological pyramid is a pictorial or graphical representation depicting how the biomass passes on to the next level. It is the method showing how bio-productivity is related to the next level. It shows, the proportionate distribution (percentage or numbers) of biomass, number of organisms and the amount of energy at different levels in a crystal clear manner. The same pyramid cannot be generalized to all ecosystems as each works differently. Any sort of calculations of energy, biomass, or numbers must include all the organisms at that trophic level otherwise the calculations might prove wrong. Sometimes a given organism may occupy more than once at different trophic levels simultaneously because a trophic level depicts just the functional level, not a species as such. For example, a dove can be represented as a primary consumer if it eats seeds and fruits, but it will become a secondary consumer if it eats insects and worms. Some of the pyramids are inverted, for example, the pyramid of biomass in an ocean is generally inverted because the biomass of fishes far exceed than the phytoplankton. As we move up the different levels of the ecosystem, energy levels keep decreasing. The following section depicts 3 There are 3 types of ecological pyramids,i,e, the pyramid of numbers, the pyramid of biomass and the pyramid of energy.


Pyramid of numbersThis is just the representation of how many numbers of organisms are distributed at each trophic level but not the biomass or energy. 


Pyramid of biomass – As the name suggests, it can depict only the amount of biomass of the organisms( species with fresh or dry weight)  at each trophic level as shown below.




Inverted biomass example is shown as below



Pyramid of energy: This represents the amount of energy  transfer from a level to the next trophic level but it doesn’t consider the biomass and the number of organisms found at each level as shown below


Related topics


Introduction to ecosystem


Succession in ecosystem


Trophic levels in ecosystem


 Productivity in ecosystem



  1. What are trophic levels? How to indicate different trophic levels in an ecosystem?
  2. Where do producers locate in the pyramid of an ecosystem
  3. List the various types of pyramids in an ecosystem.Explain briefly about pyramid of numbers.
  4. Explain the mechanism of energy flow in an ecosystem.
  5. What is biomass? Explain the pyramid of biomass. 





Course List