Primary Producer: A plant, like grass, captures energy from the sun through photosynthesis.

Primary Consumer: An herbivore, like a rabbit, eats the grass and gains energy from it.

Secondary Consumer: A carnivore, like a fox, eats the rabbit and gains energy from it.

Tertiary Consumer: A top predator, like a hawk, eats the fox and gains energy from it.

Decomposers: Bacteria and fungi break down dead organisms from all levels, releasing nutrients back into the ecosystem.

Important points:

* Energy flow: Energy is lost at each level of the food chain, typically around 10% is transferred.

* Food Webs: Real ecosystems are more complex, with organisms often feeding at multiple levels and interconnecting food chains into food webs.

Let me know if you'd like to explore a specific example of a food chain or want to dive deeper into the concept of energy transfer!