A food chain is a diagram which shows how the Sun's energy is passed from plant to animal and so on. Food chains always start with a plant, because plants are producers. The arrows point in the direction in which energy is passed.
Energy loss in food chainsEdit
Every time energy is transferred from one form to another, some is always lost as heat energy which goes into the enviroment. Along the food chain, more and more energy is lost, until when the top carnivore eats another animal, it will have only a tiny fraction of the energy originally taken into the plant.