What is a food chain?

A food chain shows how energy and nutrients transfer from one organism to another through feeding relationships always starting with a producer.

Grass → Grasshopper → Frog → Snake → Eagle
(Producer) → (Primary) → (Secondary) → (Tertiary) → (Apex)

• Each step = a trophic level
• Only ~10% of energy passes to the next level (10% law)
• Food chains interconnect to form a food web

Summary: A food chain shows the linear flow of energy from producers to consumers, with energy decreasing at each trophic level.