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Energy Pyramid

In the ecosystem, the energy is transferred when an organism eats another organism. This flow of metabolic energy can be illustrated and explained with the help of an energy pyramid. Today, in this article, we’re discussing energy pyramid, its definition, some examples, and much more.

Energy Pyramid

The sun is the source of energy for all living beings on the Earth. An energy pyramid is a graphical representation of the trophic levels (nutritional) by which the incoming solar energy is transferred into an ecosystem. The energy in an energy pyramid is measured in units of kilocalories (kcal).

Energy pyramids begin with producers at the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The highest level is the top of the food chain.

The Definition of an Energy Pyramid

An energy pyramid (also known as a trophic or ecological pyramid) is a graphical representation, showing the flow of energy at each trophic level in an ecosystem.

Any discussion of the food chain typically throws up images of a carnivorous animal chasing a deer or a buffalo. Our brains visualize one organism being hunted and eaten by another and typically associate a large, carnivorous predator at the ‘top’ of the food chain. However, this mental picture doesn’t exactly show the flow of energy through the ecosystem.

This is where an energy pyramid comes into the picture to help quantify the transfer of energy from one organism to another along the food chain. The energy decreases as you move through the trophic levels from the bottom to the top of the energy pyramid. This is because the energy is used up by the organisms at each level.

The pyramid shape is used to represent the flow of energy because of the way that energy is used up and lost throughout the system.

The Different Levels of the Energy Pyramid

The first level of the energy pyramid is represented by the ‘primary producers’ and the energy available within these primary producers. The autotrophs or the primary producers are defined as organisms that create their own food by taking their energy from the non-living sources of energy. In most cases, these are photosynthesizing plants, which use energy from the sun to create their own nutrition in the form of simple sugars. All other levels in the energy pyramid are represented by heterotrophs – organisms that produce their nutrition from organic carbon, usually from other plants and animals.

The second level of the energy pyramid consists of ‘primary consumers’ or the herbivores that feed solely on the primary producers. The third and fourth levels of the energy pyramid are made up of secondary consumers and tertiary consumers. These are carnivores and omnivores, which can feed on any of the lower levels, although mainly consume organisms from the trophic level directly beneath them. The top layer of the energy pyramid contains apex predators. These are mostly carnivorous animals that have no natural predators.

Energy Transfers

Now, let’s understand with the help of the energy pyramid what exactly this energy is that we are discussing and what is its source? The whole reason why organisms must eat is to obtain this metabolic energy, which is crucial vital for their ability to perform their basic bodily functions.

As mentioned above, the sun is the source of energy for all living beings on the planet Earth. The plants (primary producers) take in energy from the sun. However, only around 1% of the total available energy from the sun is actually absorbed into the plants (it can move through, or bounce off the plants). The plants produce metabolic energy through photosynthesis, wherein approximately 10% of their energy gets deposited in their tissues, which is available to a grazing herbivore for feeding. The plant uses the rest of the solar energy for its own metabolism, or it’s lost as heat or as waste.

Now, of that 10% that an herbivore eats from the plants, only 10% is stored in its tissues to be eaten by a carnivore. Just as in the case of the plant, the other 90% of its metabolic energy is consumed by the herbivore in all life processes such as respiration, movement, metabolic processes, excreting waste, and heat loss.

The same pattern of 10% retention of the previous level’s energy continues up the energy pyramid with each subsequent carnivore. Therefore, at each of the following trophic levels, the same amount of energy (90%) is lost as heat, while only 10% gets turned into the available bio-matter. By the time the energy reaches the top trophic level, the apex predators or the tertiary consumers will receive only 0.01% of the primary energy. Since there is so little energy available at the highest trophic level, food chains are usually limited to a maximum of six levels.

Throughout the entire energy pyramid, the decomposers (such as the bacteria, worm, and fungi) perform a very important task. These decomposers break down the tissues and other organic matter, which has not been consumed by the animals higher in the food chain or the little amount of energy remaining in the tissues of dead plants and animals. By doing so, these organisms recycle the nutrients back into the soil, playing a very crucial role in the carbon and nitrogen cycles.

Energy Pyramid- Points to Remember

  • The main source of energy is the sun. The green plants capture the solar energy to synthesize food having potential energy stored within its chemical bonds. Such potential energy transforms into kinetic energy during respiration.
  • As energy flows through different trophic levels, some energy is always dissipated as heat at each step. About 10% of the total energy is transmitted during energy flow through several trophic levels indicating a gradual decrease in the amount of energy.
  • The base of the energy pyramid denotes the position of the highest amount of energy while the amount of energy at the trophic level situated at the apex is the lowest.

In conclusion, remember that the number of organisms at any level of the energy pyramid is dependent on the availability of organisms which serve as food at the lower level.  For example, the population of particular herbivorous insects would increase if more plant food was available to them. Carrying the same argument forward, a large amount of food would be available not only to its predator, such as the frog but also to other organisms such as a bird, which feeds on that insect as a second choice. This leads to an increase in the population of that particular bird too. As a result of the increased predation, the number of herbivorous insects will go down and this, in turn, leads to a reduction in the number of its predators. This cycle, therefore ensures that the balance of nature is maintained by the availability of food.

We hope you enjoyed reading this informative article and benefitted greatly from it.

Learn all about the Ecosystem and the features and classification of Fungi.


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