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Where does the rest of the 90% energy go?

Energy flow is an important aspect of understanding the structure and function of ecosystems. In any ecosystem, energy flows through different levels of the food chain starting from producers, primary consumers, secondary consumers, and tertiary consumers. At each level, only a certain percentage of energy is transferred to the next level through the food chain, the remaining energy is used for various metabolic processes within the organism or is lost as heat. In this blog post, we will be focusing on the question, where does the rest of the 90% energy go?

The 10% Rule

The answer to this question lies in the 10% rule which states that only 10% of the energy available at one trophic level is transferred to the next trophic level. For example, if 1000 units of energy are available in the producer level, only 100 units of energy will be transferred to the primary consumer level. The remaining 900 units of energy are used by the producer for carrying out different life processes such as photosynthesis, respiration, growth, reproduction, and repair. Similarly, when the primary consumer eats the producer, only 10% of the energy obtained from the producer is available for transfer to the secondary consumer. The remaining 90% is again used for the primary consumer’s life processes.

Where does the energy go?

As we have seen in the 10% rule, the majority of the energy obtained by an organism is used for its life processes. This includes the energy used for carrying out various metabolic processes like digestion, respiration, excretion, and assimilation, all of which require energy. Some of the energy obtained by an organism from its food, however, is not used in its body and is instead lost to the environment as heat through various processes like radiation, convection, and conduction.

Let’s take the example of a predator hunting for prey. When the predator captures and eats its prey, only a small amount of energy is transferred to the predator. The remaining energy is lost to the environment during different metabolic activities that the prey had performed in its life, such as hunting prey, digesting food, running, or swimming. As a result, predators must consume a large amount of prey to fulfill their energy requirements, and this creates a chain of energy flow up the food chain.

Energy Loss During Respiration

One of the primary uses of energy in an organism’s body is for respiration. During respiration, the food consumed is oxidized to produce energy required for carrying out various life processes. However, not all of the energy obtained from food is transformed into the energy required for these processes. Instead, a considerable amount of energy is lost in the form of heat. In fact, studies have shown that only about 40% of the energy obtained from food during respiration is used for the metabolic processes, while the remaining 60% energy is lost as heat.

Heat Loss and Thermoregulation

Another significant factor affecting energy loss is heat loss. Whenever an organism’s temperature is higher than its surroundings, heat is lost to the surroundings as per the laws of thermodynamics. Thermoregulation, or the ability of an organism to maintain its body temperature, is, therefore, an essential part of an organism’s physiology. During thermoregulation, energy is used to maintain or alter an organism’s body temperature. This results in the loss of energy to the environment, ultimately leading to a reduction in the amount of energy available for use in the organism’s metabolic processes.


In conclusion, the rest of the 90% energy is used by the organism for its life processes or is lost to the environment in various ways. The 10% rule plays a critical role in the flow of energy through different levels of the food chain, and the rest of the energy plays an essential role in an organism’s life processes, such as respiration, digestion, and thermoregulation. Understanding energy flow and loss is, therefore, essential for understanding the structure and function of ecosystems and their sustaining of life.


What happens to the 90 percent of energy that isn t transferred?

In ecosystems, energy transfer is a fundamental process that sustains life. Energy flows in the form of food from one organism to another in a food chain. However, not all of the energy gets transferred from one organism to another. About 90 per cent of energy may be lost as heat (released during respiration), through movement, or in materials that the consumer does not digest.

The reason for this energy loss is due to the second law of thermodynamics, which states that in a closed system, energy tends to move from a higher state of order to a lower state of order. In other words, energy gradually becomes more dispersed and less useful. In an ecosystem, the energy that is lost in the form of heat or other means becomes dissipated into the environment and cannot be used again by the organisms.

While a large amount of energy loss may seem wasteful, it is actually an important feature of ecosystem functioning. The energy that is lost from one trophic level is used to drive the next level. For instance, the energy stored in undigested materials can be transferred to decomposers, which break down the organic matter into simple inorganic molecules that can be reused by other organisms. This process is known as nutrient cycling, and it helps to maintain the balance of matter and energy in an ecosystem.

Furthermore, the energy that is lost also contributes to the stability of the ecosystem. If all the energy was transferred from one organism to another, the ecosystem would be highly vulnerable to disturbances such as disease, predation, and natural disasters. By retaining a significant proportion of energy within the ecosystem, the species can buffer against these disturbances and recover more easily from them.

The 90 per cent of energy that is not transferred from one organism to the next in an ecosystem gets lost in various ways and becomes unavailable to the organisms. However, this energy loss is actually crucial for maintaining ecosystem sustainability. The energy that is lost drives vital processes like nutrient cycling and contributes to the resilience of the ecosystem.

Why does 90% of energy lose trophic levels?

The transfer of energy in an ecosystem follows a specific pattern called trophic levels, which consists of a series of steps or levels in a food chain. The first trophic level includes producers, such as plants, algae, and certain bacteria, that convert light energy from the sun into chemical energy through photosynthesis. The second trophic level includes herbivores, such as cattle, rabbits, and insects, that consume the producers. The third trophic level includes carnivores, such as lions, wolves, and eagles, that consume the herbivores, and so on.

As energy is transferred from one trophic level to the next, it is important to note that not all the energy is passed along. In fact, a significant amount of energy is lost at each trophic level, resulting in only about 10% of the energy being transferred to the next level. The remaining 90% is lost as heat or used up in metabolism.

There are several reasons for this energy loss. Firstly, organisms at the lower end of the food chain use some of the energy they acquire from the sun in photosynthesis to carry out their own metabolic processes. This results in a loss of energy before it even reaches the first trophic level. Secondly, not all parts of an organism are eaten by the predator. For example, a lion may consume a zebra but only eats a portion of the meat, while the rest is left untouched and eventually decomposes. Thirdly, not all the food that is ingested can be digested and assimilated by the predator. The remaining undigested material is expelled as waste.

Finally, energy is also lost as heat during respiration, which is the process by which organisms break down food molecules to release energy. This heat is then lost to the environment, and cannot be used in higher trophic levels.

Energy loss in trophic levels is a natural phenomenon that is inevitable. Although the loss of energy may seem significant, it is important to remember that this is what sustains life in the ecosystem. Without the transfer of energy from one trophic level to the next, organisms in higher levels would not be able to survive.

What is the 10 percent rule of energy?

The 10 percent rule of energy, also known as Lindemann’s law, was proposed by ecologist Howard T. Odum and later popularized by ecologist Raymond Lindeman. The rule states that only around 10 percent of energy in a food chain is transferred from one trophic level to another. The rest of the energy is utilized for other metabolic processes and some is released as heat.

This law explains the inefficiency of energy transfer between trophic levels. Trophic levels are the different levels in an ecosystem where organisms exist, starting from producers to primary and secondary consumers and finally to apex predators. The transfer of energy between these levels is necessary for the maintenance of the ecosystem.

Producers, such as plants, use the sun’s energy in photosynthesis to produce organic matter, which is then consumed by herbivores, or primary consumers. The energy that herbivores obtain from consuming these plants is only about 10 percent of the total energy produced by the plants. When carnivores, or secondary consumers, consume these herbivores, only about 10 percent of the energy obtained by the herbivores is transferred to the carnivores.

The 10 percent rule highlights the importance of maintaining a balance in ecosystems. Any disruption in one trophic level can have significant effects on the rest of the levels. For example, if there is a decrease in the number of producers, there will be a cascading effect on the rest of the ecosystem. Primary consumers will have less food, which will result in a decrease in the number of secondary consumers, and eventually apex predators will also be affected.

The 10 percent rule of energy helps ecologists understand the inefficiency of energy transfer between trophic levels. It also emphasizes the importance of maintaining a balance in ecosystems to ensure the survival of all species in the food chain.