Students should be able to describe the differences between the trophic levels of organisms within an ecosystem. • Trophic levels can be represented by numbers, starting at level 1 with plants and algae. Further trophic levels are numbered subsequently according to how far the organism is along the food chain. • Level 1: Plants and algae make their own food and are called producers. • Level 2: Herbivores eat plants/algae and are called primary consumers. • Level 3: Carnivores that eat herbivores are called secondary consumers. • Level 4: Carnivores that eat other carnivores are called tertiary consumers. Apex predators are carnivores with no predators. • Decomposers break down dead plant and animal matter by secreting enzymes into the environment. Small soluble food molecules then diffuse into the microorganism.