Food web game: build food chains in three ecosystems
What is a food web?
A food web is a map of who eats whom in an ecosystem. In other words, it joins every food chain in one place into a single network. Each arrow points from the food to the animal that eats it. So the arrows also show which way the energy flows. The game above holds three food webs on one page: the Amazon rainforest, a Pacific kelp forest and a meadow.
Every food web starts with the Sun. Plants and algae capture sunlight and turn it into food, so ecologists call them producers. Next, animals eat the producers, and other animals then eat those animals. Finally, decomposers recycle whatever dies. As a result, nutrients flow back into the soil or water, ready for the next round.
Food chain vs food web: what is the difference?
A food chain is one straight path of energy, from a producer up to a top predator. For example, giant kelp, then a purple sea urchin, then a sea otter, then an orca is one food chain. A food web, by contrast, shows all the chains in an ecosystem at once. After all, most animals eat more than one thing, and several predators usually hunt them. So real ecosystems look like webs rather than ladders.
That difference matters. In a single chain, losing one link would starve everything above it. In a web, however, a predator can often switch to other prey. Therefore, food webs with many links tend to be more stable. That is one reason biodiversity is so important, and I explain the idea further in higher diversity, higher resilience.
Trophic levels: producers, consumers and decomposers
Ecologists sort the members of a food web into trophic levels, which simply means feeding levels. The colours below match the game, so you can spot each level on the map. Tap any animal for my full guide to it.
Herbivores eat only plants, while carnivores eat other animals. Omnivores, such as the red fox and the piranha, eat both. Scavengers like vultures and condors clean up dead animals, so they belong in the web too. You can meet them in my guide to scavenger animals. At the top sit apex predators such as the jaguar and the orca. Nothing hunts them once they are adults.
Energy flow in a food web and the 10% rule
Energy moves up a food web, but most of it never arrives. Each animal burns energy to move, grow and keep warm, and much of it escapes as heat. On average, only about 10% passes from one trophic level to the next. Ecologists call this the 10% rule, although real values range from roughly 5% to 20%.
Raymond Lindeman worked out this energy loss from his studies of a small lake in Minnesota (Lindeman, 1942). His idea explains two patterns you can see in the game. First, food chains rarely run longer than four or five links, because too little energy is left at the top. Second, top predators are always rare. In fact, a whole forest of fruit trees supports only a handful of jaguars. Open the Energy tab above, then drag the slider to watch the numbers change.
Three food webs on one page
The game holds three ecosystems, and each tab works the same way. Pick one and tap a species, and its links light up. Then switch tabs to compare a forest, an ocean and a field.
Amazon rainforest food web
In the Amazon, fig trees, seeds and river grasses feed howler monkeys, sloths, agoutis, tapirs and capybaras. Meanwhile, jaguars, harpy eagles, anacondas and black caimans compete at the top. The rainforest food web also reaches into the river, since piranhas eat fallen seeds and pink river dolphins hunt piranhas. To see where each animal lives, climb through my rainforest layers interactive.
Kelp forest food web
Along the Pacific coast of North America, giant kelp builds an underwater forest. Purple urchins graze it, while sea otters, sunflower sea stars and octopuses keep the grazers in check. Out in open water, phytoplankton feed zooplankton and sardines. Seals, sevengill sharks, great white sharks and orcas then hunt at the top. My kelp forest guide explains why this ocean food web matters so much.
Meadow food web
The meadow is the food web closest to most homes. Here, grasses and wildflowers feed rabbits, mice, grasshoppers and caterpillars. Robins eat the insects and earthworms, and then foxes, hawks and owls hunt the small mammals. Meanwhile, earthworms and fungi recycle dead plants into soil. You can even grow a small version yourself with a wildlife-friendly garden.
Meet all 46 species in the game
Here is every plant, animal and decomposer from the three webs. Filter them by ecosystem or by trophic level, then tap a card to read more.
Trophic cascades: what happens when a species disappears?
Remove one species, and the effects can ripple through the whole food web. Ecologists call this a trophic cascade. The kelp forest shows it best. Sea otters eat about a quarter of their body weight every day, much of it urchins. So when the fur trade wiped otters out, urchins exploded and mowed the kelp down to bare rock.
In the 1990s, the same story played out again in Alaska’s Aleutian Islands. Orcas began to eat sea otters, probably because seals and sea lions had declined. Otter numbers then crashed, urchins boomed and the kelp forests collapsed (Estes et al., 1998). Later, between 2014 and 2017, a marine heatwave and a sea star wasting disease hit northern California. Purple urchins increased about 60-fold, and more than 90% of the bull kelp canopy disappeared (Rogers-Bennett & Catton, 2019).
Predators shape other ecosystems too. For example, read what happened when white sharks left False Bay. Similarly, beavers rebuild whole rivers as ecosystem engineers. My guide to keystone species covers the animals that hold many webs together.
How people change food webs
Most food webs today feel human pressure from several directions at once. Here are five of the biggest. The What if? tab also lets you test three of them for yourself.
Biomagnification is the sneakiest of the five. Some poisons never break down, so they build up in every animal that eats contaminated food. As a result, top predators carry the highest doses. For instance, DDT once thinned the eggshells of eagles and other birds of prey for exactly this reason. Lead works in a similar way for scavengers.
On a field trip to Baja California about condor conservation, I learned how this hits the California condor. Hunters shoot deer, and the carcasses they leave behind can hold lead fragments. Condors then scavenge them, and the lead poisons them, causing disease and death. During that trip, I watched a few condors flying high above us, and it was such a wholesome moment. Read their full comeback in the California condor story.
Protection can rebuild a food web, though. When fishing stops, predators return, just as they did at Cabo Pulmo in Mexico. Learn how that works in my guide to marine protected areas.
Food webs I have seen in the wild
The best food web lesson I ever had came while snorkelling on a whale shark tour off Holbox, Mexico. That snorkel was one of the best for action. We came across the head of a big dead fish. On one side, two sea turtles were eating it. On the other, a juvenile nurse shark was eating from the opposite end. It was an epic battle of survival, and a perfect reminder that scavengers are part of every food web.
Coral reefs hold the busiest food webs I know. In Koh Lipe, Thailand, I watched small fish sheltering in reef nurseries. Nearby, fish were eating coral and then defecating, which returns that material straight to the reef. Now and then, a bigger fish ate another one right in front of me. The coral at Amed in Bali and at several spots around Coron in Palawan was just as alive. Discover more coral reef fish and coral islands.
Seagrass meadows are underwater food webs too. I have dived among seagrass in the Red Sea and in parts of Australia, with coral fish and sea turtles all around. On my Australia lap, at Illaroo, I also found a wobbegong near a seagrass bed. Dugongs, for their part, eat almost nothing but seagrass.
One food web I watched grow from nothing. At university, I built a pollinator garden with a professor and other students. Over time it filled up with bumblebees, wasps, spiders, beetles and many other insects. Seeing that whole process of nature creation showed me how quickly a web assembles once the producers are in place. My guide to pollinators lists who to plant for.
Cesar Medina, conservation biologist
5 food web examples from around the world
Food webs exist in every habitat on Earth, from deserts to the deep sea. Here are five classic examples, each written as one simple food chain. The first three are also playable in the game above.
How to explain a food web to a child
Start with lunch. Ask your child what they ate, and then trace it back to the Sun. For example, a cheese sandwich leads to a cow, then to grass and finally to sunlight. Next, open the Meadow tab above and tap the rabbit. Its green arrows show what it eats, while its red arrows show who eats it.
After that, switch to Build a chain mode and let them link the Sun to a fox. Then try the What if? tab together and remove the foxes. Ask them to predict what happens to the rabbits before you press play. That small prediction turns the lesson into a game, and the quiz makes a fun final check.
A food web shows who eats whom, and how the Sun’s energy travels from plants to animals.
Food web worksheets and lessons for teachers
Teachers can use the game as a ready-made lesson. First, project it and let the class vote on each What if? prediction before you run it. Students can also race each other in Build a chain mode. Since the quiz changes every round, it works well as a quick exit ticket.
For printables, my Teachers Pay Teachers store has ready-to-use biome worksheets. A food web worksheet that matches this game is on the way too.
More wildlife interactives
Frequently asked questions
What is a food web in a short sentence?
A food web is a network of linked food chains that shows who eats whom in an ecosystem.
What is a simple definition of a food chain?
A food chain is a single line of living things in which each one eats the one before it. It starts with a plant or alga and usually ends with a predator.
What is a food web in the ecosystem?
It is the feeding network that links every producer, consumer and decomposer in an ecosystem. As a result, it shows how energy and nutrients move between them.
What are 5 examples of the food web?
Five classic examples are a rainforest, a kelp forest, a meadow, the Antarctic Ocean and a coral reef. Each one has producers at the base, consumers above them and decomposers recycling the dead.
How do you explain a food web to a child?
Call it a map of who eats whom. Start with the Sun, then follow the arrows from plants to plant eaters and on to meat eaters.
What happens if one species is removed from a food web?
Its prey usually increase, while its predators lose a meal. Those changes then spread to other levels, which ecologists call a trophic cascade.
Where do decomposers go in a food web?
Decomposers sit beside the web rather than on top of it. They feed on dead material from every level and return the nutrients to the producers.
Why is energy lost in a food chain?
Animals use most of their energy to move, grow and stay warm, and a lot escapes as heat. Therefore, only about 10% passes on to the next level.
