What is a sentence for the word food chain?

Animals and plants are always invovled in a food chain.

A food chain is a series of plants and animals each of which is eaten as food by the one above in the series.

Humans are at the top of the food chain when only considering plants, or animals which humans kill and eat. However, the food chain can quickly change when a human puts him or herself too close to an alligator, shark, or any large, hungry predator.