The levels of a food chain (food pyramid) are called Trophic levels. The trophic level of an organism is the level it holds in a food pyramid.

• The sun is the source of all the energy in food chains. Green plants, usually the first level of any food chain, absorb energy from sunlight to make their food by photosynthesis. Green plants (autotrophs) are therefore known as ‘Producers’ in a food chain.
• The second level of the food chain is called the Primary Consumer. These consume green plants. Animals in this group are usually herbivores. Examples include insects, sheep, caterpillars, and even cows.
• The third in the chain are Secondary Consumers. These usually eat up the primary consumers and other animal matter. They are commonly called carnivores, and examples include lions, snakes, and cats.
• The fourth level is called Tertiary Consumers. These are animals that eat secondary consumers.
• Quaternary consumers eat tertiary consumers.
• At the top of the levels are Predators. Predators are animals that have little or no natural enemies. They feed on prey and are the ‘bosses’ of their ecosystems. Prey is an animal that predators hunt to kill to feed on. Predators include owls, snakes, wild cats, crocodiles, and sharks. Humans can also be called predators.

When an organism dies, detrivores (like vultures, worms, and crabs) eat them up. The rest is broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues. Decomposers start the cycle again.