Under the sea ice, in near darkness, a small silvery fish snaps up tiny drifting crustaceans. A ringed seal catches the fish. On the ice above, a polar bear waits by the seal’s breathing hole, and an Arctic fox waits for the bear’s leftovers. That is the Arctic food web in one scene.
The Arctic food web has two linked halves. In the sea, tiny plankton feed small fish such as Arctic cod, which feed seals, belugas, narwhals and seabirds; seals then feed polar bears. On the tundra, plants feed lemmings, hares and caribou, which feed Arctic foxes, snowy owls and wolves. Sea ice connects both halves.
Key takeaways
- Key fish: Arctic cod link plankton to seals, belugas, narwhals and seabirds.
- Top predator: the polar bear, which mainly eats ringed and bearded seals.
- Key land prey: lemmings; in northeast Greenland four predators depend on them.
- Weak point: sea ice. Losing it threatens seals, walruses and polar bears.
What does the Arctic food web look like?
Think of two pyramids joined at the coast. The ocean pyramid runs from plankton to Arctic cod to seals and whales to polar bears and killer whales. The land pyramid runs from tundra plants to lemmings, hares and caribou to foxes, owls and wolves. Arctic foxes and polar bears cross between the two, scavenging and hunting on both ice and land.
Picture it: the Arctic food web
Arrows point from food to eater. Underlined names open our full article.
Polar bear · Killer whale
Arctic cod · clams and other seafloor animals
Copepods, krill-like crustaceans, algae
Lemmings · Arctic hare · Caribou · Muskox
Willow · sedges · grasses · lichens
Cross-links: Arctic foxes scavenge seals killed by polar bears; polar bears also eat Arctic foxes at times. Sources listed at the end.
Why is Arctic cod so important?
Arctic cod is the main link between tiny plankton and large animals. It eats copepods and other small crustaceans, then becomes food for seabirds, ringed seals, narwhals, belugas and other fish, according to NOAA Fisheries. NOAA scientists say it may be the Arctic fish most vulnerable to warming water.
Ringed seals also depend on cod-family fish: they dominate the seals’ diet from late autumn through spring (NOAA Fisheries).
What do polar bears eat in the Arctic food web?
Polar bears sit at the top of the sea-ice food chain. Their main prey is ringed and bearded seals, which they hunt at breathing holes and open cracks in the sea ice. A bear can eat more than 45 kg (100 lb) of blubber in one meal (Polar Bears International). Ringed seals are their primary prey (NOAA Fisheries).
Polar bears also take belugas, and walruses are hunted by both polar bears and killer whales (NOAA Fisheries; ADF&G). More in what polar bears eat and polar bear adaptations.
Where do walruses and whales fit in?
Walruses feed on the seafloor, eating clams, snails, worms, sea cucumbers and other soft invertebrates; some, mostly males, sometimes eat seals and seabirds (ADF&G). Belugas eat fish such as cod, herring and salmon, plus octopus, squid, crabs and clams. Narwhals eat Arctic cod, turbot, squid and shrimp, diving to about 1,200 m (3,937 ft) (NOAA Fisheries).
See what walruses eat, how belugas find food with sound and how much a beluga weighs.
How does the tundra food web work?
On land, lemmings are the engine. In northeast Greenland, collared lemmings are the main prey of four predators: the stoat, Arctic fox, snowy owl and long-tailed skua. A model based on field data predicted the lemmings’ roughly 4-year boom-and-bust cycle, driven by stoats and steadied by the other three predators (Gilg et al. 2003).
Snowy owls may feed almost entirely on lemmings and often breed only in lemming-rich years (Audubon). Arctic fox numbers also rise and fall with lemming and vole cycles (ADF&G). Arctic hares eat mostly willow and are hunted by foxes, wolves, lynx, stoats, snowy owls and falcons (ADW). Caribou eat lichens in winter and fall prey to wolves and bears (ADF&G).
Picture it: a lemming year
Imagine a playground that is packed one year and almost empty the next, over and over every few years. That is life for lemmings, and the owls, foxes and skuas that eat them must boom and bust too.
How do the sea and land food webs connect?
The Arctic fox is the clearest bridge. In summer it eats lemmings, voles and nesting seabirds; in winter many foxes go onto the sea ice to eat the remains of seals killed by polar bears (ADF&G). Polar bears sometimes eat Arctic foxes too; see do polar bears eat Arctic foxes?
Ice seals are a food source for polar bears and for Arctic Indigenous peoples, eat fish and invertebrates, and help recycle nutrients, so the IUCN calls them keystone species (IUCN 2025).
What happens to the Arctic food web when sea ice melts?
Sea ice is the floor of the marine food web. Seals breed, rest and moult on it, walruses rest on it between dives, and polar bears hunt from it. In October 2025 the IUCN moved the hooded seal from Vulnerable to Endangered, and the bearded and harp seals from Least Concern to Near Threatened, naming sea-ice loss as the main threat (IUCN).
On land, a Greenland model found that warming would likely lengthen lemming cycles and lower peak numbers, which would hurt the predators that depend on lemming years (Gilg et al. 2009). Read why polar bears are at risk.
Three things you can do: cut your energy use and talk about climate change, the main threat to sea ice; never buy products made from Arctic wildlife without knowing they are legal and sustainable; and support Arctic research and Indigenous-led conservation groups.
Myths about the Arctic food web
Myth: Polar bears eat penguins.
Fact: Penguins live in the Southern Hemisphere, not the Arctic. See do polar bears eat penguins?
Myth: Lemmings jump off cliffs in mass suicides.
Fact: Lemming numbers crash because of predators and natural cycles. The model by Gilg and colleagues explains the 4-year cycle with predation alone (Gilg et al. 2003).
Myth: Walruses dig up clams with their tusks.
Fact: Walruses use their tusks to haul out, break ice, fight and defend themselves, not to dig for food (ADF&G).
Test yourself
1. Which small fish links plankton to seals and whales?
Arctic cod.
2. What is a polar bear’s main prey?
Ringed and bearded seals.
3. Name two predators that depend on lemmings.
Any two of: Arctic fox, snowy owl, stoat, long-tailed skua.
Where to next?
➡️ Go wider: where polar bears live⬆️ Go deeper: Arctic fox adaptations🔀 Go sideways: what eats polar bears?
Frequently asked questions
What is the top predator in the Arctic?
On the sea ice it is the polar bear, which mainly eats ringed and bearded seals. In the water, killer whales also hunt belugas and walruses. On the tundra, wolves are the largest predators.
What are the producers in the Arctic food web?
In the sea, the producers are microscopic algae, eaten by tiny crustaceans such as copepods. On land, they are plants such as willows, sedges and grasses, and lichens, which caribou eat in winter.
What would happen if Arctic cod disappeared?
Animals that rely on it, including ringed seals, belugas, narwhals and seabirds, would lose a fatty, high-energy food. NOAA scientists warn that Arctic cod may be the Arctic fish most vulnerable to warming waters.
Sources
- NOAA Fisheries (2015). NOAA Fisheries scientists successfully spawn and hatch Arctic cod in captivity.
- NOAA Fisheries. Ringed seal.
- NOAA Fisheries. Beluga whale.
- NOAA Fisheries. Narwhal.
- Polar Bears International. Polar bear diet.
- Alaska Department of Fish and Game. Walrus; Arctic fox; Caribou.
- National Audubon Society. Snowy owl.
- Animal Diversity Web. Lepus arcticus.
- Gilg, O., Hanski, I. and Sittler, B. (2003). Cyclic dynamics in a simple vertebrate predator-prey community. Science 302: 866-868.
- Gilg, O. et al. (2009). Climate change and cyclic predator-prey population dynamics in the high Arctic. Global Change Biology.
- IUCN (10 October 2025). Arctic seals threatened by climate change, birds decline globally: IUCN Red List.
Sources checked 12 October 2026.
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