Food Chains and Food Webs
This lesson talks about food chains and food webs in our environment.
Food Chains
A food chain is a flow of energy from a green plant (producer) to an animal (consumer) and to another animal (another consumer) and so on. In this lesson we are going to talk all about food chains and food webs in the environment.
All organisms need energy to live. Energy is obtained from food. Green plants are the only organisms that can capture energy from sunlight and make their own food.
Try Food Chains Quiz 1 and Food Chains Quiz 2 at the end of the lesson to check your knowledge about food chains and food webs.
Producers in food chains
A green plant should always be the first link of a food chain. Green plants are the only organisms that can directly get the sun’s energy and make their own food through a process called photosynthesis.
Grass is a good example of producers
Green plants are the best producers in the environment
Herbivores are animals that only feed on plants.
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Omnivores are animals that eat a variety of food of both plant and animal origin.
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Carnivores and Top Predators in food chains
Carnivores are animals that only feed on other animals.
Carnivores are also known as the top predators as they are at the highest point of the food chain. Top predators have a little or no enemies. They usually consume all lower levels and are not consumed by any other animals until they die.
Lions, tigers, crocodiles, eagles are the best examples of top predators.
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Eagle is a best example of a top predator
Lion is a best example of a top predator
Leopard is a best example of a top predatorPrey
Prey is an animal that a predator feeds on. For example, a lion feeds on a zebra. So, the zebra is the prey of the lion.
Example of a good predator and its prey
All animals depend on plants directly or indirectly for food and energy.
A chart that shows direct and indirect consumers
Primary Consumers in food chains
Primary consumers are the second link of a food chain. They are usually herbivores that eat green plants or sometime omnivores that eat both plants and animals.
Let’s look at some types of food chain in the examples below.
The green plants are the food of all herbivores that are primary consumers.
Example of a food chain with two links showing the producer and the primary consumer
Secondary Consumers in food chains
Secondary consumers are the third link of a food chain. They can be either omnivores or carnivores.
The herbivores are the food for carnivores that are secondary, tertiary or quaternary consumers.
Example of a food chain with three links showing the producer, the primary consumer and the secondary consumer
Tertiary and Quaternary Consumers in food chains
Tertiary consumers are the fourth link of a food chain while quaternary consumers are the fifth link of a food chain. They are usually the carnivores that are top predators.
Secondary consumers are the food for carnivores or top predators that are tertiary or quaternary consumers.
Example of a food chain with four links
Sometimes tertiary consumers can be the food for quaternary consumers.
Example of a food chain with five links
Likewise, step by step, the energy in food flows from the producers to consumers.
Scavengers and decomposers in food chains
When an organism dies, it is eventually eaten by scavengers and broken down by decomposers like bacteria and fungi, and the exchange of energy continues in the environment.
- Crows
- Vultures
- Hyenas
- Ants
- Worms
- Crabs
Crows, vultures and hyenas are the best examples of vertebrate scavengers while ants are good invertebrate scavengers in the environment. They eat dead bodies of animals and plants.
Example of a crow who is a best scavenger in the environment
Bacteria, fungi, algae, lichens are the best examples of decomposers. They break down dead bodies of plants and animals and let the essential nutrients in the dead matter mix with the ecosystem again, so that no waste would pile up.
A wooden bench covered with lichens
A food chain is a flow of energy from a green plant (producer) to an animal (consumer) and to another animal (another consumer) and so on.
- A food chain shows us a series of living things that depend on each other for food energy.
- A food chain shows us the relationship between the animals and plants in a habitat.
- A food chain shows us the way energy flows through a habitat.
- There are usually three or four organisms in a food chain:
Each of these organisms in a food chain is called a link. These links make a food chain.
- Food chains usually start with a producer or a green plant :
This is the link where energy from the sun enters the food chain.
Examples of Food Chains Diagrams
Food Web
In nature the food chains are not as direct as we’ve seen them in our discussion. The food chains are highly cross linked (connected) and highly complicated. In any habitat there may be many kinds of animals that feed on the same plants and there may be many predators that feed on the same kinds of prey. Therefore there will be several food chains in any habitat. These food chains are inter-linked and they form food networks in the habitat.
A food web is a type of a food network with several inter-linked food chains in a habitat.
Food Web Diagram