Autotrophs also are referred to as primary producers . For completeness, we should mention the pathway known as chemosynthesis . Some producer organisms, mostly specialized bacteria, can convert inorganic nutrients to organic compounds without the presence of sunlight. There are several groups of chemosynthetic bacteria in marine and freshwater environments, particularly those rich in sulfur or hydrogen sulfide gas. Like chlorophyll-bearing plants and other organisms capable of photosynthesis, chemosynthetic organisms are autotrophs.
Many organisms can only obtain their energy by feeding on other organisms.
These are called heterotrophs . Heterotrophs also are called consumers . We shall begin with a consideration of primary production, and in the next lecture we shall examine what happens to this energy as it is conveyed along a food chain. The Process of Primary Production Production is the creation of new organic matter. When a crop of wheat grows, new organic matter is created by the process of photosynthesis, which converts light energy into energy stored in chemical bonds within plant tissue.