What are the 4 trophic levels in a food chain?

An organism may not always occupy the same trophic level, it can differ accordingly based on the food chain. 

There are 4 trophic levels in a food chain, they are –

1. Producers, 
2. Herbivores (primary consumers), 
3. Carnivores (secondary consumers), 
4. Predators (tertiary consumers).

Further Readings – 

1. Energy Flow in Ecosystem
2. Biodiversity – Species, Genetics & Ecosystem