Abstract
All living organisms need a source of energy to remain alive. There are many ways whereby they obtain this energy by following various pathways of the food chain. Plants are by far the main primary producers of food. They take approximately 1% of the light energy from the sun that falls on them and convert it to organic compounds that serve as food for many animals and also for some non-photosynthetic plants such as mushrooms. On the other hand, carnivorous animals obtain their energy by eating other animals, and a few carnivorous plants eat animals. Because of a variety of energy relationships, the food chain is sometimes referred to as the food web. The food chain can be generalized to the simple fact that almost all animals obtain their energy directly or indirectly from plants. An exception would be the large, 1.3-meter tubeworms that live deep in the ocean along warm water vents where there is no light. They obtain their energy from bacteria which in turn obtain their energy from sulphur compounds; but on land, animals obtain their energy from plants. Without plants, most other organisms cannot survive.