Transfer of biomass

The arrows in a food chains show the transfer of biomass from one organism to another. An example of a food chain is:

maize → locust → lizard → snake

Some of the energy from the sun transferred by maize when it photosynthesises is transferred to the locusts when they eat the plant. Then some of the biomass in the locust is transferred to the lizards when they are eaten and so on.

Energy available in producers

Energy available in producers

Not all of the biomass is passed from the maize plants to the locusts. In fact, only about 10% of the biomass is transferred from each trophic levels to the next. The remaining 90% is used by the organism to complete life processes. Biomass can be lost between stages because not all of the matter eaten by an organism is digested. Some of it is excreted as waste such as solid faeces, carbon dioxide and water in respiration and water and urea in urine.

Because only around 10% of the biomass at each trophic level is passed to the next, the total amount becomes very small after only a few levels. So food chains are rarely longer than six trophic levels.

curriculum-key-fact
We do not put the Sun at the bottom of a food chain even though the producing plants or algae transfer energy from the Sun during. This is because the Sun is not a living organism.

In fact, only about 1% of the energy from the Sun that reaches the plant's leaves is used by the plant during photosynthesis. This sounds small but is still enough to power almost all food chains on the planet.