Life on earth cannot exist without energy. Growth, movement, reproduction, healing and the internal body functions all need some energy. In the natural ecosystem, nearly all the energy is produced by one source, the sun. Photosynthesis is the process in which plants will absorb sunlight and transform it into chemical energy stored in their tissues. This energy and stored energy is the basis on which other life is based. Complex life on earth would not have been possible without this constant transformation of the sun into usable energy.

Producers are plants and other photosynthetic organisms since they generate their own food. They constitute the foundation of any land and water habitat. Herbivores feed on plants and receive the stored energy on plant tissues. Carnivores feed on herbivores and accumulate energy which initially was of plant origin. Omnivores eat plant and animal food, which attracts energy in a variety of ways. This chain of passing of energy between the producers and the consumers constitutes what is referred to as a food chain.

A food chain is a simplified mechanism demonstrating energy flow within one organism to another. Natural ecosystems, however, are not often basic. In the vast majority of cases, organisms consume more than one category of food, and organisms are consumed by more than one predator. Due to this complexity, scientists do not use simple chains, but food webs. Food web refers to a system of food chains within an ecosystem that illustrates the numerous ways that energy can circulate within a food web.

Food webs depict the relationship among life. The transformation of one population can affect so many others. When one of the species goes extinct with respect to a particular prey, its predators might need to go hungry. When the population of predators reduces, there is a risk of the prey population growing beyond sustainability. The changes may spread across the entire ecosystem, with a ripple effect on the plant population, soil composition, and even the water resources.

The utilization of energy among organisms is not very efficient. Whenever an organism eats, it does not use all the energy to translate into body mass. A good portion of the energy is devoted to respiration, movement, digestion, and body temperature. The amount of energy lost in form of heat is significant. Due to such inefficiency, a small proportion of energy transfers between troic levels.

This trend describes why the number of plants, herbivores, and predators in an ecosystem is much higher than in a herbivores one respectively. The huge numbers of predators need enormous amounts of energy at the bottom of the food web. In the case of the population decrease of plants, the whole system will be unstable. This limitation of energy aids in the explanation of natural population limits of the ecosystem.

Another difference between food webs is in ecosystems. A grassland food web would not appear like a forest food web. Coral reef food web is not like the freshwater lake food web. The species and interactions of each ecosystem are unique, but the principle of flow of energy is the same.

The food webs are altered with changes in the seasons. During warm seasons, the growth of plants is high hence yielding plentiful food to herbivores in temperate regions. An increase in the number of predators can be expected in response to an increase in the number of prey. In low temperatures, food supply reduces and most of the organisms move, hibernate or slow down.

Invisible life force is the flow of energy through the ecosystems. This interrelates light with plants, animals with decomposers, nutrients with plants, and animals with animals.The study on energy flow promotes respect in ecological boundaries. It brings to the fore the fact that the eventual collapse of the ecosystem is because of unsustainable use of the resources.

Food webs are the invisible structure of the world.They illustrate how life is related in terms of energy.They demonstrate why it is necessary to protect whole ecosystems.A healthy energy flow represents a healthy ecosystem.Healthy ecosystems represent a healthy planet.