2. Energy Flow: Food Chains & Webs

Almost all of an ecosystem's energy starts as sunlight. From there it flows from one organism to the next, and every organism has a role based on how it gets energy.

• Producers (plants, algae) make their own food by photosynthesis — they capture energy first.
• Consumers get energy by eating other organisms: herbivores eat plants, carnivores eat animals, omnivores eat both.
• Decomposers (fungi, bacteria) break down dead material and recycle nutrients back into the ecosystem.

A food chain shows a single path of energy (grass → grasshopper → frog → snake). A food web links many chains together and is more realistic, because most organisms eat — and are eaten by — more than one kind of thing.

The arrows always point from the food to the eater, showing the direction energy moves. Grass → grasshopper means the energy stored in grass passes to the grasshopper when it's eaten.

⚠️ Common misconception: the arrows do not mean 'chases' or point from predator to prey. They show energy flowing from the food to the consumer.

💡 Tip: producers start every chain (right after the Sun), and arrows follow the energy.