Organisms occupy a trophic level in the food chain based on their source of nutrition. [1]
A species may occupy more than one trophic level in the same ecosystem at the same time.
For example, a bear is an omnivore. When it eats leaves, berries and other plant products, it occupies the primary trophic level but whern it eats meat and fish, it occupies the secondary trophic level. [1]