The living organisms that eat the producers are then considered to be the primary consumers, similarly to how the first person to buy a car is the primary consumer of that particular car. The primary consumers now have energy, and other organisms that are called secondary consumers can eat them. Secondary consumers are those organisms whose main food source is primary consumers. This is similar to you as the second consumer of the car. Even the secondary consumers have energy to pass on and can then be consumed by the tertiary consumer. These consumers are those who feed mostly on secondary consumers.