The Sun is the original source of energy for almost all organisms on the Earth. The way energy passes through an ecosystem is described as energy flow.
Animals/consumers obtain the food made by plants/producers through feeding.
Herbivores (plant eating animals) are primary consumers.
Carnivores (animals who eat other animals) are secondary consumers while those that feed on secondary consumers are tertiary consumers.
This sequence of feeding (producers, primary consumers, secondary consumers and tertiary consumers) shows the flow of energy.
The different stages in the feeding sequence are also referred to as trophic levels. Producers are trophic level 1; primary consumers are trophic level 2 and so on.
Specific feeding sequences (and therefore flow of energy) can be represented as a food chain.
Arrows between each organism show the direction of:
Food webs show a number of food chains that are interlinked due to the organisms involved living in close proximity.
Most organisms will have more than one food source that can be seen in a food web but not a food chain.
Energy is lost between each trophic level.
From the Sun to the plant (producer), energy is lost when light is reflected off the leaf or passes through the leaf missing the chloroplasts. However, with no shortage of sunlight, this is not an issue.
Between each trophic level only 10-20% of the energy is transferred – a loss of 80-90%.
Energy is lost due to:
Shorter food chains are more energy efficient as energy is lost at each stage.