Changing life in the Arctic illustration for a story about food webs and Arctic ecology

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Food chain: food chains show “who eats whom”. They are possible pathways for how nutrients and energy can flow through an ecosystem......more

Food web: the connections between all the organisms that eat and are eaten by each other in a particular place... more

Trophic level: a position in a food web, based on relationships with other organisms in the food web....more

Arctic Food Webs

Across the expanse of sea ice, you see a polar bear, standing perfectly still, staring down. She looks surprisingly yellow, in contrast to the brilliant white snow and ice around her. While you may not think there are any other organisms nearby, there are.

an Arctic cod is alive but surrounded by ice

This tiny Arctic cod uses antifreeze proteins in its blood to survive in literally freezing waters. Image by NOAA via Flickr.

Algae floats under the ice the polar bear stands on. Copepods, which look like tiny shrimp, dart around the water. They are eating algae and other tiny plants and animals. Arctic cod make their home here too, where food is plentiful and they can hide in pockets of water under ridged ice floes.

The polar bear is waiting for a seal that is hunting fish underwater to come up to the surface for air. The Arctic is full of life, and one way to think about all that life is in terms of who eats whom.

Trophic Levels

When one organism eats another, it moves stored energy around the food chain. The amount of energy that moves around can be represented by a pyramid. In the pyramid, the lowest level, or first trophic level, are the primary producers. These organisms, like plants and algae, turn the sun's energy into their own source of food. This process is called photosynthesis.

crustacean zooplankton under a microscope

These microscopic shrimp, crabs, and other crustaceans are called "zooplankton." They are some of the Arctic's primary consumers. Image by NOAA via Flickr.

Next up in the pyramid, we have the primary consumers–they are the ones who eat the producers. Each consumer needs to eat a lot of producers. This means that the number of consumers who can survive depends on the number of producers in the area.

When these organisms are eating each other, the stored energy is being passed along the food web. Living is expensive in terms of energy. About 90% of the energy animals get from their food is used up to stay healthy and do daily activities. Only the remaining 10% or so can be used to grow. That 10% is what can be passed onto the next trophic level when an animal is eaten.

Below is a chart of trophic levels with Arctic animals:

TROPHIC LEVELHOW IT GETS FOODARCTIC EXAMPLE

1st Trophic Level:

Primary Producers

Photosynthesis

Ice algae,

phytoplankton

2nd Trophic Level

Primary Consumers

Eats producers

Krill, clam, 

ice copepod

3rd Trophic Level

Secondary Consumers

Eats primary consumers

and some producers

Arctic cod, 

squid

4th Trophic Level

Tertiary Consumers

Eats secondary consumers

and some primary consumers

Ringed seal, beluga

whale, polar bear

Scavengers

Eats all levels of consumers 

that have recently died

Arctic fox

Decomposers

Eats all levels of consumers

and producers that have died

Bacteria

Where the Walrus Fits

a polar bear scavenging a dead narwhal

Even top predators like this polar bear can sometimes act as scavengers. Here is one eating part of a dead, beached whale. Image by C. Fallows and collaborators via Wikimedia Commons.

The trophic levels are a good rule of thumb, but it’s not always quite so simple. Most animals eat from a mix of the trophic levels, and some animals don’t fit nicely into one category at all. One such animal is the walrus.

Walrus are big animals, and not many other animals eat them. This would mean they’re a tertiary consumer. But we know that walrus like to eat clams, and clams are a primary consumer. Does this mean walrus are part of the third trophic level instead of the fourth? Not necessarily.

In a real ecosystem, most species don’t fit into perfectly defined boxes. Normally walruses eat things like clams, shrimp, crabs, soft corals, and sea cucumbers. But, when food is scarce, they are known to eat almost anything they can get, including fish like arctic cod. 

Food Chains

Food chains show how energy moves through different groups of animals. Animals have to eat to survive and to get energy to do their daily activities. A food chain only shows one direction of how energy is transferred. In nature, it is usually more complex as more than one animal might hunt a specific species.

Food Webs

An illustration of an arctic food web

The Arctic food web. Click for more detail.

When many food chains are linked together they create a food web. Most animals have many food sources and also have many predators. A food web shows these multiple pathways for energy to flow within an ecosystem. This helps give a more realistic view into what’s really happening in nature.


This section of Ask A Biologist is based upon work supported by the National Science Foundation under Grant No. 1928235.

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Bibliographic details:

  • Article: Arctic Food Webs
  • Author(s): Emma Goethe, Cecilia Knaggs, Leah Shaffer
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: July 27, 2022
  • Date accessed: May 31, 2023
  • Link: https://askabiologist.asu.edu/arctic-food-webs

APA Style

Emma Goethe, Cecilia Knaggs, Leah Shaffer. (2022, July 27). Arctic Food Webs. ASU - Ask A Biologist. Retrieved May 31, 2023 from https://askabiologist.asu.edu/arctic-food-webs

American Psychological Association. For more info, see http://owl.english.purdue.edu/owl/resource/560/10/

Chicago Manual of Style

Emma Goethe, Cecilia Knaggs, Leah Shaffer. "Arctic Food Webs". ASU - Ask A Biologist. 27 July, 2022. https://askabiologist.asu.edu/arctic-food-webs

MLA 2017 Style

Emma Goethe, Cecilia Knaggs, Leah Shaffer. "Arctic Food Webs". ASU - Ask A Biologist. 27 Jul 2022. ASU - Ask A Biologist, Web. 31 May 2023. https://askabiologist.asu.edu/arctic-food-webs

Modern Language Association, 7th Ed. For more info, see http://owl.english.purdue.edu/owl/resource/747/08/

A polar bear patiently waits by the edge of the ice, hoping to catch a seal to eat. Image by NASA via Flickr.

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