Producers: (plants)
Plants use carbon dioxide, light, water, and the green pigment chlorophyll found in their leaves to produce food for themselves. During this process the plants produce oxygen for us. Thus plants are producers as they produce their own food. (Autotrophic organisms)
Consumers:
Animals are consumers (including us). All animals rely on plants to produce food so that the animals could either eat the plants (herbivorous) or eat the animals who eat the plants (carnivores) or both (omnivore). Thus its fair and easy to say that consumers have a heterotrophic feeding methods and are present in the world today because of producers.
Decomposers
Decomposers or Saprophytic organisms are also heterotrophic animals. Decomposers or Saprophytic organisms are micro-organisms that break down complex organic matter into simple inorganic matter. Decomposers get their energy from decaying plants or animals.