Trophic levels are the feeding position in a food chain such as primary producers, herbivore, primary carnivore,etc.
1st. Photosynthsis (green plants) They're the "producers"
2nd. Herbivore - animal that feeds on plants. Known as "Primary Consumers"
3rd. Carnivore - animal that feeds on flesh. Known as "Secondary Consumers"
4th. Top carnivore - the biggest animal - known to be at the top of the food chain. Known as "Tertiary Consumers"
The levels work in a sequence of feeding of one animal upon another in food transfers.
Begins with light energy from photosynthesis from plants, then being eaten by herbivores the energy is changed to chemical energy.
Example of a food chain: rose plant -- aphids -- beetle -- chameleon -- hawk. This followers the labeled numbers above.
Eventually for example like the hawk dies and its remains are broken down by decay-causing bacteria and fungi.