what is 10% law? explain with an example how energy flows through different trophic levels.

Asked by hels145 | 4th Aug, 2008, 09:36: PM

Expert Answer:


As we pass from one trophic level to the next, only 10% of energy is transferred from the first trophic level to the next. This is because a lot of energy is lost to the surroundings and rest is utilised by the organism.

We can understand this better using an example.

When green plants are eaten by primary consumers, lot of energy is lost as heat to the environment. Some energy is used by the consumer into doing work and digestion whereas rest is used for growth and reproduction. About 10% of the eaten food is turned into its body and made available to the next level of consumers. So the actual energy passing to the next trophic level is only 10%.

Grass -> Grasshopper -> Frog -> snake -> hawk

Here, a part of the solar energy is captured by grass which uses it to produce food. About 10% of this captured energy is passed on to grasshoppers. Here, large amount of energy is lost as heat, some goes into digestion and doing work and rest towards growth. Again 10% of the food eaten by the grasshopper is made available to the next trophic level, comprising of frogs. In this way energy flows further from frog to snake and from snakes to the final trophic level, made up of hawks..

Another example would be

Dead organic matter -> Microrganisms like bacteria, fungi etc. -> Detritivores like earthworms, nematodes etc.  -> Predators like snakes, frogs etc.

Answered by  | 5th Aug, 2008, 09:08: AM

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