If your child is learning third or fourth grade science, you'll want to make sure he has a solid understanding of how a food chain works. Different organisms in our ecosystem rely on one another as a food source. Understanding what organisms are producers and what organisms are consumers is a vital part of elementary science.
A food chain worksheet will help your students understand the basics of how a simple food chain works. It breaks down the chain with a circle of organisms, including:
The student must number the items in order from one to five, with the one showing where the energy starts and each number going around the circle consecutively to show the chain of events. Key points the student will learn include:
- The food chain starts with producers, such as plants.
- Consumers eat the producers or other consumers.
- Decomposers take care of the consumers after they die, fertilizing the land.
- The process starts again.
Reinforce the worksheet by having the students call out different animals that are herbivores and carnivores. You can also take the lesson a step further by discussing how animals like bears or wild boars are omnivores and may server different roles in the food chain at different times.
To use the worksheet, click the image to print the page. In order for the page to print, you must have the latest version of Adobe Acrobat Reader.
Teaching a More Complex Food Chain
Most food chain diagrams are shown with a simple representation of a food chain, but if a food chain is made up of who eats whom, then you can imagine that a chain can become pretty complex. The diagram included with the printable worksheet in this lesson plan shows the sun, to a plant, to a herbivore, to a carnivore to decomposers in a circle. However, the actual food chain is much more complex and made up of many different species and levels within each of these categories. You also have scavenger birds and animals that are omnivores and eat both plants and animals.
A more complex food chain might have the following steps:
- The sun shines down on a leafy plant.
- Part of the leafy plant is eaten by a rabbit.
- Another part of the plant is eaten by a deer.
- A coyote catches the rabbit and eats it.
- A scavenger bird picks the rest of the meat off the carcass.
- Decomposers take care of the rest of the rabbit.
- The deer is killed by a human hunter who eats the deer.
You can see how the food chain becomes extremely complex and is not necessarily circular in nature. If one were to draw lines showing where organisms get their food, it would look more like a tangled web of lines back and forth than a true circle. A network with many food chains is thus called a food web.
Each food chain is made up of:
- Primary Producers: These are plants and other basic organisms. They gain their energy from the sun via a process known as photosynthesis or from chemosynthetic bacteria, which is found in hydrothermic vents in the oceans. Primary producers are also called autotrophs.
- Primary Consumers: Next are the organisms that eat the primary producers. These are also called herbivores. These are animals that feed only on autotrophs, but are usually eaten by other animals (carnivores).
- Secondary Consumers: This level is made up of organisms that eat the primary consumers. This might be a snake that feeds on a rabbit.
- Tertiary Consumers: These organisms eat the secondary consumers, such as a snake. This is simply a larger predator, but still feeds on another complex organism. An example might be a hawk that eats a fish that ate the worm that fed on the bacteria in the pond.
- Quaternary Consumers: These eat the tertiary consumers. For example, a wolf captures an injured hawk and eats it.
- Top Predator: A top predator is the highest in a given food chain. Some examples might be a mountain lion or a grizzly bear. These animals are large, fast, strong, or all of the above. They do not have natural predators.
- Decomposers: When an organism dies, it is further broken down by worms, crabs and vultures and then by the decomposers of bacteria and fungi.
Some organisms do not always retain the same role in the food cycle. An example would be the grizzly bear. It can shift from being a primary consumer when it eats berries to being a secondary consumer when it eats fish to being the top predator.
There are some key concepts you need to make sure your students understand about food chains. Food chains are constantly changing and in motion. There is a cycle to each ecosystem and specific organisms that live within that ecosystem. The food chain in a desert is different than the food chain in the ocean. Ensure that your students understand the main concepts of food chains by quizzing students on the basic terms, such as herbivore, primary producer, etc. If the student understands those concepts, he can adapt and figure out the order of a food chain in different environments. The concept of a food chain is a big concept that states that organisms gain energy from somewhere. The concept is then broken down in the stages of gaining energy or giving energy back to the earth.