Obviously, we all know that living organisms require energy for many purposes, be it for locomotion, repairing body tissues or for growth. Also, we know that it is impossible to create energy from this. This implies that energy needs to be transferred among the ecosystem for them to utilise it. The Sun acts as the main source of all energy which is available to us living organisms on earth. Plants and phytoplankton are autotrophs, meaning that they produce their own energy from the sun. Other animals, including humans, are heterotrophs and obtain their energy by consuming other organisms.  This flow of energy can be depicted through a food chain or a food web. At the bottom of a food chain is always the primary producer. In terrestrial ecosystems most primary producers are plants, and in marine ecosystems, most primary producers are phytoplankton. Both produce most of the nutrients and energy needed to support the rest of the food chain in their respective ecosystems.

Only a certain percentage of the total energy level will be available to the organism at the higher trophic level. This is because a lot of biomass is wasted as it is excreted as waste, converted to heat etc. Thus, the next consumer does not have access to biomass and energy . This is why usually only one tenth of the energy stored as biomass is passed on to adjacent trophic levels.This is known as “the 10 percent rule” and it limits the number of trophic levels an ecosystem can support. This is the principle which justifies the increased prices of meat compared to that of vegetables and crops, as it takes around tenfold the energy to produce per the same weight. I hope this article has been successful in explaining this concept to you !