1. Producers: These are organisms that make their own food through photosynthesis, like plants and algae. They form the base of the food chain.

2. Consumers: These are organisms that obtain their energy by consuming other organisms. They can be herbivores (eating plants), carnivores (eating other animals), or omnivores (eating both plants and animals).

3. Decomposers: These are organisms that break down dead plants and animals, returning nutrients to the soil. They are essential for recycling matter in the ecosystem.

These levels interact and depend on each other to maintain a balanced ecosystem.