visit http://www.makemegenius.com for more free science videos. All living things need food to have energy which help them to grow and move.A food chain tells how each living thing gets its food and how most of living beings are dependent on each other for their energy requirement.It is also called food web or energy pyramid.A food chain always starts with a producer, which in most of the cases is a plant and it ends with a predator,it is at the top of the food chain. Consumers, scavengers,herbivores and decomposer form important constituents of a food chain.