Food Chain Vs. Food Web

Food Chain Vs. Food Web

Miss Irizarry's Classroom

What do we study to learn about an animal species? We study its anatomy and its behaviors. We study its habitat,

its diet, and its enemies. The last two topics are essential for us to understand where the animal stands in its food

chain and in its food web.

But what is a food chain? What is a food web? And what is the difference between a

food chain and a food web?

To answer these three questions, let's use zebras as our example.

Zebras roam freely in the African savannah. They feed on grasses. When zebras graze, they often share their space

with animals like rhinos, warthogs, and antelopes that also eat plants. Zebras have no problem sharing their space

with these herbivores. Zebras' biggest fear is to bump into hungry carnivores! Lions, cheetahs, leopards, and

crocodiles would all love to eat them!

Multiple Choice

Plants and algae are usually on the first trophic level in a food web.

• True

• False

Lions, for instance, eat zebras. Zebras eat grasses. There is an invisible chain linking the fate of these three living

things. We call this invisible chain a food chain.

Multiple Choice

Food chains are the same thing as food webs

• True

• False

Now, let's expand our focus to include warthogs. Like zebras,

warthogs are grazers. Also like zebras, warthogs are afraid of lions. Hence, we know that we can establish another

food chain involving grasses, warthogs, and lions. If we continue this exercise, we will map out many individual

food chains. All of these individual food chains form a food web unique to the African savannah.

Both zebras and warthogs are in the second level of their respective food chains as well as in their food web.

Above them (the third level) are lions, and below them (the first level) are plants. We call each level a trophic

level. Usually, the higher an animal is in its food chain or food web, the bigger and more powerful it is.

Multiple Choice

Which of the following about the food chain is correct?

• A food chain is also known as a food web.

• A food chain always contains three trophic levels.

• Lions are on the first trophic level in their food chain.

• Usually, the higher an animal is in its food chain, the bigger and more powerful it is.

Multiple Choice

If you have to get rid of one animal from the following choices so the remaining correctly form a food

chain, which one will you eliminate?

• Snakes

• Rats

• Elephants

• Nuts or seeds

Of course, not all food chains have three trophic levels. For instance, algae are consumed by fish, fish are

consumed by seals, and seals are consumed by polar bears. Algae, fish, seals, and polar bears make up a four-trophic-level food chain.

Multiple Select

Which of the following statements about the food web is correct? (Please choose two of the best answers.)

• A food chain is a collection of many different food webs.

• The food web in a tropical rainforest is different from that in a desert.

• While the interruption of a food chain may be disastrous to our environment, the interruption of a food

  web is not.

• A food web is a collection of many different food chains

It is also important to know how disastrous our environment may become if a food chain or a food web gets

interrupted. One example of this is when Thomas Austin brought twenty-four rabbits from England in 1859. He

released them on his property in southern Victoria, Australia.

Nobody could have foreseen that those twenty-four rabbits would multiply into millions in the next ten years! Rabbits were a foreign species in Australia. They had no natural predators and faced no threats in their new home. Rabbits are ruthless plant eaters. These rabbits were

responsible for the extinction of many Australian plants and plant-eating animals!

Multiple Choice

Why did many Australian plant-eating animals become extinct?

• Because they were killed by ostriches, introduced to Australia in 1859

• Because their food source was eaten by rabbits, introduced to Australia in 1859

• Because they were killed by koalas, introduced to Australia in 1598

• Because their food source was eaten by chickens introduced to Australia in 1598

Multiple Choice

Look at this food chain: Human <== Chicken <== Earthworm <== decaying vegetable matter. Which

organism is on the second trophic level?

• human

• decaying vegetable matter

• earthworm

• chicken

Multiple Choice

Look at this food chain: Human <== Chicken <== Earthworm <== decaying vegetable matter. Which of the following animals can potentially substitute for "human"

• elephant

• hippopotamus

• crocodile

• fungus