All lifeforms need energy to survive. Energy is the resource that allows organisms to do things. What kinds of things might an organism do with energy? The answer to this question is as varied as the lifeforms that use energy. Some, like the African Lion, use energy to chase after prey. Other lifeforms, like many creatures we find in the depths of the Earth's oceans, use energy to create their own light. Living things use energy to grow, to defend themselves, and to move around.
With so many living things around us using energy every day, you might ask where all this energy comes from. The main source of energy on the Earth today comes from the Sun. The energy found in your body, that you use to run, jump and play sports, was originally produced by the Sun.
Plants use sunlight to create their own food. Many animals then eat the plants, taking this energy into their own bodies. Other animals then eat these plant eaters, passing the Sun's energy from one organism to another.
The amount of energy in all the coal and oil reserves on Earth is equal to only 20 days of sunlight that reaches the Earth.
