Why Are There Food Chains?

Food chains are simply a mental construct we use to organize and understand the interdependency of living things. A food chain can contain plants, animals, or both.

Food source

• All living things must have a source of energy (food) to exist. The type of food depends on the mechanism the plant or animal has to convert food to energy.

Making food

• Many organisms use light as an energy source. Water and nutrients in their environment enable them to convert light into energy. Some is stored as food for other organisms that lack the physiological ability to transform light directly into energy.

Making Food

• The food chain for a life form can be as broad or narrow as its energy conversion mechanisms allow. One that can convert any source of biological material into energy obviously has more food sources available than those that can convert only specific kinds or parts of other organisms.

The Chain

• Microorganisms that decompose any organic matter are at the bottom of the food chain. As we travel up the chain, fewer basic food sources are available. For instance, large animals are at the top of their food chain, but may consume only a few specific foods.

Humans

• Humans---the most advanced life form---have complex mechanisms to convert many kinds of food to energy. This helps ensure survival, even when these energy sources increase or decline.

Interdependency

• It should be noted that a harmful item that enters the food chain at any level can produce a major survival problem for all other organisms interdependent in that chain.