From http://library.thinkquest.org/11353/food.htm:Producers: these include all green plants. These are also known as autotrophs, since they make their own food. Producers are able to harness the energy of the sun to make food. Ultimately, every (aerobic) organism is dependent on plants for oxygen (which is the waste product from photosynthesis) and food (which is produced in the form of glucose through photosynthesis). They make up the bulk of the food chain or web.
This means that the producer I create must be able to produce it's own food. The other characteristics of the creature can be set by me. This makes the task a lot easier!