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Food Chains and Food Webs


 

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. In this lesson we are going to talk about Food Chains and Food Webs in the environment. Try Food Chains Quiz 1 and Food Chains Quiz 2 at the end of the lesson to check your knowledge.

food-web

 

Producers of a food chain

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.

 

food chains producer grass

Grass is a good example of producers

 

   

green-plants2

Green plants are the best producers in the environment

What are herbivores?

Herbivores are animals that only feed on plants.

 

food chains - herbivores

A sheep is an example of a herbivore

food chains - herbivores

Elephants are examples of herbivores

food chains - herbivores

A hippopotamus is an example of a herbivore

food chains - herbivores

A wallaby is an example of a herbivore

 

What are omnivores?

Omnivores are animals that eat a variety of food of both plant and animal origin.

 

food chains - omnivores

A dog is an example of an omnivore

food chains - omnivores

A cat is an example of an omnivore

food chains - omnivores

Humans are examples of omnivores

food chains - omnivores

A squirrel is an example of an omnivore

 

Carnivores and Top Predators

Carnivores are animals that only feed on other animals. These 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 for top predators.

 

food chains - carnivores

A cheetah is an example of a carnivore

food chains - carnivores

A crocodile is an example of a carnivore

food chains - carnivores

A tiger is an example of a carnivore

food chains - carnivores

Meerkats are examples of carnivores

 

 Some other examples of top predators

 

food chains - top predators

Eagle is a best example of a top predator

food chains - top predators

Lion is a best example of a top predator

food chains - top predators

Leopard is a best example of a top predator

 

Prey

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.

 

prey-and-predator

Example of a good predator and its prey

 

All animals depend on plants directly or indirectly for food and energy.

 

food chains - direct indirect consumers

A chart that shows direct and indirect consumers

Primary Consumers

 

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.

 

The green plants are the food of all herbivores that are primary consumers.

 

food chains - primary consumers

Example of a food chain with two links showing the producer and the primary consumer

 

Secondary Consumers

 

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.

 

secondary-consumer

Example of a food chain with three links showing the producer, the primary consumer and the secondary consumer

 

Tertiary and Quaternary Consumers

 

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. 

 

food chains tertiary consumers

Example of a food chain with four links

 

Sometimes tertiary consumers can be the food for quaternary consumers.

 

food chains 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

When an organism dies, it is eventually eaten by scavengers like crows, vultures, ants, worms and crabs and broken down by decomposers (mostly bacteria and fungi), and the exchange of energy continues in the environment.

Crowsvultures 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.

 

food chains - scavengers

Example of a crow who is a best scavenger in the environment

 

Bacteria, fungi, algae, lichens are the 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.

food chains - decomposers

A wooden bench covered with lichens

 

What is a food chain?

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.

 

What does a food chain show us?

1) A food chain shows us a series of living things that depend on each other for food energy.

 

2) A food chain shows us the relationship between the animals and plants in a habitat.

 

3) A food chain shows us the way energy flows through a habitat.

 

What are the features of a food chain?

1) 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.

 

2) Food chains usually start with a producer or a green plant :

This is the link where energy from the sun enters the food chain.

 

Food Chains

 

food-chains

 

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.

 

What is a food web?

A type of a food network with several inter-linked food chains in a habitat is called a food web.

 

A Food Web

 

food-web

 

Try Food Chains Quiz 1 and Food Chains Quiz 2