FOOD CHAIN
Danlal D, Chiras*
In the biological world you are one of two things, either a producer or a consumer. (Only rarely can you be both.) Producers are the organisms that support the entire living world through photosynthesis. Plants, algae, and cyan bacteria are the key producers of energy-rich organic materials. They are also called autotrophs (from the Greek root “troph”- to feed, nourish), because they literally nourish themselves photo synthetically, that is, by using sunlight and atmospheric carbon dioxide to make the food materials they need to survive. Consumers feed on plants and other organisms and are called heterotrophs [hetero = other], because they are nourished by consuming other organisms.
Consumer organisms that feed exclusively on plants are called herbivores. Cattle, deer, elk, and tomato hornworms are examples. Those consumers that feed exclusively on other animals, such as the mountain lion, are carnivores. Those consumers that feed on both paints and animals, such as humans, bears, and raccoons, are omnivores.
The interconnections among producers and consumers are visible all around us. Mice living in and around our homes, for example, eat the seeds of domestic and wild plants and, in turn, are preyed on by cats and hawks.
A series of organisms, each feeding on the preceding one, forms a food chain. Two basic types of food chains exist in nature: grazer and decomposer. Grazer food chains, like the one discussed above, are so named because they start with plants and with grazers, organisms that feed on plants. In the second type-the decomposer, or detritus, food chain waste which comes from plants and animals.
Food chains are conduits for the flow of energy and nutrients through ecosystems. The sun’s energy is first captured by plants stored in organic molecules, which then pass through the grazer and decomposer food chains. In addition, plants incorporate a variety of inorganic materials such as nitrogen, phosphorus, and magnesium from the soil. These chemical nutrients become part of the plant’s living matter, When the green plant is consumed, these nutrients enter the food chain. They are eventually returned to the environment by the decomposer food chain.
