1 Food Chains and Food Webs-Low

Food Chains and Food Webs Written by Kira Freed

Introduction Ana eats a breakfast of oatmeal, yogurt, and orange juice before going to school. The food she takes in will give her energy for learning, gym, and other morning activities. Where did the energy in her food come from? This book explores how living things get the energy and matter they need to survive. You will learn how one living thing depends on another and that all living things depend on the Sun's energy. You will also learn what happens when a food source is taken away.

Producers and Consumers Living things are either producers or consumers. Producers produce, or make, their own food. Green plants are the main producers. They produce food by using the Sun's energy to combine water with a gas from the air. This process is photosynthesis. Without the Sun's energy and the producers that use it for photosynthesis, most living things on Earth would not survive. Consumers cannot make their own food. Instead they depend on producers for food. Consumers eat, or consume producers or other consumers, Producers and consumers depend on each other in many ways.

Food Chains Food chains show how one living thing depends on another living thing for food, as each link in a paper chain depends on the one before and after it. Food chains also show how energy and matter move from producers to consumers. Since producers make food, they are the first link in a food chain.

A food chain has only one link for producers but many links for consumers. Primary consumers are living things that eat plants. They are the next link in a food chain. Grasshoppers and elephants are both primary consumers, or herbivores. Herbivores often have special body parts that help them get and use the energy stored in certain plant parts.

To review, the first link in a food chain is the producers, or plants. The second link is primary consumers, or herbivores. The third link is secondary consumers—animals that eat the herbivores. These animals are carnivores, or meat eaters. When people think of carnivores, they often think of animals such as tigers and wolves. But other animals, such as insect- eating spiders and some bats, are also carnivores. So are penguins, bald eagles, and other fish eaters. What comes after primary consumers (which eat plants) and secondary consumers (which eat herbivores)? Many food chains also have tertiary consumers—carnivores that eat other carnivores. For example, let's say a mouse eats grass. Then a snake eats the mouse. A hawk that eats the snake is a tertiary consumer Word Wise Primary 1st Secondary 2nd Tertiary 3rd