4.7 Energy Transfer

4.7 Explain why only about 10% of energy is transferred from one trophic level to the next

This Pyramid of Energy shows that of the 100% of energy from the producer only 10% makes it to the primary consumer and again only 1% of the original amount of energy makes it through to the Secondary consumer.

But Why?
If 100KJ of producer energy was eaten by the primary consumer, only 10% of this (10KJ) will become tissue of that animal. This is because the primary consumer has to travel to find it's food and respire, using up much of the 100kj of energy, What's more not all the energy can be digested by the animal, for example the cellulose and so the energy stored in here simply passes through the animal and is excreted as faeces.
Then the secondary consumer eats the 10KJ of primary consumer, but this animal still must respire and travel using up much of the energy and once again, not all the animal tissue can be digested so not all the energy is reclaimed, resulting in the secondary consumer only receiving 1KJ of the original 100KJ of energy