What is a food chain? All organisms need energy in the form of food to grow, move and carry out body functions. They depend on outside factors, including other plants and animals, for this energy. Plants need energy from the sun and nutrients found in the soil to grow. Animals eat plants or other animals to gain the energy they need to survive. Food chains and food webs show how different species work together to make an ecosystem. Larger animals eat smaller animals which in turn eat plants that gain energy from the sun. This linking of animals and plants is called a food chain. Food chains vary in different areas and ecosystems and can involve any number of species. To investigate food chains and webs you will need to look at food in a different way. Food is not necessarily a fillet of fish, mushrooms, insect or piece of deer. It is a form of energy which moves from one organism to another. A plants' food is the sun's rays, which provide it with the energy needed to survive. Some forms of algae use chemicals from gases in volcanoes to create energy. Food is simply a method of gaining the energy needed to stay alive. The actual feeding patterns in any environment are complex and are difficult to describe using a single food chain. The flow of energy between the plants and animals in an ecosystem is actually a network of many interlocking food chains and is called a food web.   Why do food chains form? Because plants or animals need to feed on other plants or animals a series of steps can be used to explain how energy travels from one organism to the next. A food chain is formed when plants are eaten by small animals, which are eaten by large animals which are in turn eaten by even larger animals. An example of this linking can be seen in the following food chain: The chain is created because different organisms have different energy needs. The bigger the animal the more food it needs to survive. 90% of an animal's energy intake is used for body functions - only 10% is used for actual bone, muscle and body mass growth. Plants require much less energy to grow, therefore they need less food than animals. A wallaby needs to eat 10 kilograms of grass each day to gain its energy needs, and a dingo must consume about 3 wallabies each week to gain enough energy to survive.

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