Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass.
-- G. Tyler Miller, Jr., American Chemist (1971)
A trophic level is each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy.
Sunlight is NOT a trophic level.
The first trophic level is always the primary producer. These are plants (autotrophs) that use photosynthesis to produce their own food.
The second trophic level is always the primary consumer. These organisms are always herbivores or organisms that consume plants in order to get food.
The third trophic level is always the secondary consumer. These organisms are always carnivores or organisms that consume animals in order to get food.
The forth trophic level is always the tertiary consumer. These organisms are always carnivores or organisms that consume animals in order to get food.
Sometimes there is a fifth trophic level which is the quaternary consumer. These organisms are always carnivores or organisms that consume animals in order to get food.
