A food web is a detailed interconnecting diagram that shows the overall food relationships between organisms in a particular environment. It can be described as a “who eats whom” diagram that shows the complex feeding relationships for a particular ecosystem.
The study of food webs is important, as such webs can show how energy flows through an ecosystem. It also helps us understand how toxins and pollutants become concentrated within a particular ecosystem.
Food webs can also help us study and explain how the diversity of species is related to how they fit within the overall food dynamic. They may also reveal critical information about the relationships between invasive species and those native to a particular ecosystem.
What is A Food web?
A food web consists of all the food chains in a single ecosystem. Each living thing in an ecosystem is part of multiple food chains. Each food chain is one possible path that energy and nutrients may take as they move through the ecosystem. All of the interconnected and overlapping food chains in an ecosystem make up a food web.
Food webs connect many different food chains and many different trophic levels. Food webs can support food chains that are long and complicated, or very short.
In a typical food chain, we might see something like a mouse eating a plant and then being eaten by an owl. However, the mouse isn’t the only thing eating the plants. There are probably many different animals eating them.
For example, grass in a forest clearing produces its own food through photosynthesis. A rabbit eats the grass. A fox eats the rabbit. When the fox dies, decomposers such as worms and mushrooms break down its body, returning it to the soil where it provides nutrients for plants like grass.
This short food chain is one part of the forest’s food web. Another food chain in the same ecosystem might involve completely different organisms. A caterpillar may eat the leaves of a tree in the forest. A bird such as a sparrow may eat the caterpillar.
A snake may then prey on the sparrow. An eagle, an apex predator, may prey on the snake. Yet another bird, a vulture, consumes the body of the dead eagle. Finally, bacteria in the soil decompose the remains.
Structure
In a food web, organisms are arranged according to their trophic level. The trophic level for an organism refers to how it fits within the overall food web and is based on how an organism feed.
Broadly speaking, there are two main designations: autotrophs (producers) and heterotrophs (consumers). Autotrophs make their own food while heterotrophs do not. Within this broad designation, there are five main trophic levels: primary producers, primary consumers, secondary consumers, tertiary consumers, and apex predators.
| Trophic Level | Desert Biome | Grassland Biome | Pond Biome | Ocean Biome |
| Producer (Photosynthetic) | Cactus | Grass | Algae | Phytoplankton |
| Primary Consumer (Herbivore) | Butterfly | Grasshopper | Insect Larva | Zooplankton |
| Secondary Consumer (Carnivore) | Lizard | Mouse | Minnow | Fish |
| Tertiary Consumer (Carnivore) | Snake | Snake | Frog | Seal |
| Quaternary Consumer (Carnivore) | Roadrunner | Hawk | Raccoon | Shark |
First, the sun’s energy allows producers to grow and make their own food. Next, many organisms eat the producers to get energy. Notice how it’s not just one organism feeding on the producers; many animals include these plants in their diet.
At the next level up, we have omnivores and predators eating many organisms below them. They even dip into the aquatic food web in the middle. Finally, we have an apex predator at the top, which feeds on many different levels of consumers.
An example of a food web is a deciduous forest ecosystem. In the deciduous forest, plants like grass are producers. They are eaten by primary consumers, such as rabbits, which are eaten by secondary consumers, such as foxes. The tertiary consumer in this food web could be a hawk or other large predator. Finally, mushrooms and earthworms are decomposers.
A food web shows us how these different trophic levels within various food chains interconnect with one another as well as the flow of energy through the trophic levels within an ecosystem.
Food Web Examples
In an ocean ecosystem, Phytoplankton and algae form the bases of aquatic food webs. They are eaten by primary consumers like zooplankton, small fish, and crustaceans. Primary consumers are in turn eaten by fish, small sharks, corals, and baleen whales. Top ocean predators include large sharks, billfish, dolphins, toothed whales, and large seals. Humans consume aquatic life from every section of this food web.
In a grassland ecosystem, plants, grass, and tree form the bases of the grassland ecosystem. Deer, mice, and even elephants are herbivores, they eat grasses, shrubs, and trees and act as a primary consumer. The animals like foxes, jackals, snakes, frogs, lizards, birds, etc., are carnivores feeding on herbivores and act as secondary consumers. Top predators include Jaguars, Sumatran and Malayan tigers, lions, leopards, hyenas, cheetahs, African wild dogs, and wolves who feed on other animals called carnivores.
In a desert ecosystem, a mouse, chipmunks, squirrels, rabbits, and deer that eats seeds and fruits is a primary consumer. A secondary consumer may be a spider, bird, or snake that eats a mouse chipmunks, squirrels, rabbits, or deer. A fox, coyotes, eagles, and owls may prey on birds and snakes. Top desert predators’ bobcats and mountain lions are top predators.
Examples of African Grassland (Savanna) Food Web:
This is an African Savanna Food Web. See if you can identify all the parts of the food web that make this a functioning, healthy ecosystem. Look for:
- The Producers – the trees, shrubs, and grass.
- The Primary Consumers – the zebras and elephants.
- The Secondary Consumers – the cheetah, hyena.
- The Scavengers – the termites, vultures, and hyenas.
- The Decomposers or Detritivores – mushrooms, insects, and microorganisms.
Food Web Diagram
A simple interaction of 3 food chains representing a general food web diagram.
Food webs can likewise help us study and make sense of how the variety of species relates to how they fit inside the general food system. In a food web, life forms are organized by their trophic level.
The trophic level for an organism alludes to how it fits inside the general food web and depends on how an organism takes care of it. In straightforward terms, the food web is basically founded on who feeds from whom in an environmental local area. Food webs are otherwise called consumer-resource systems.
Importance of studying Food web
- To understand what food chains and food pyramids are.
- To study how a food web works.
- To understand the interactions between organisms and their relationships in an ecosystem.
- Helps in the understanding of natural selection.
- What are trophic levels in the food pyramid?
- It shows how energy is transferred from the bottom to the top of the energy pyramid.
- How energy flows across an ecosystem.
- To understand how an organism depends on another in food pyramids.
Food Webs Are Easily Affected by Change
Changing any part of the web will cause all the other parts to also change. If you remove the mouse from the web in the picture above, a few things can happen.
First, because there are no mice to eat, the lynx population might not have enough food to support itself. This population might decline, which would then cause the snakes to not have enough food. This pattern would keep happening until the entire ecosystem has been changed.
You can think of the food web like a literal spider web: If you touch any part of it, the rest will shiver and shake. Pulling out a single strand from the web can cause strands to cross or even cause the whole thing to come crumbling down. This can happen when an ecosystem is disturbed, like when a non-native species is introduced.
Changes to ecosystems can be devastating, but they can also lead to things like rapid evolution that creates a variety of new adaptations and new webs.