In this lesson, we will learn what a food web is. We will also discuss the 2 main classifications of organisms found in a food web. We will give an example of an ocean food web and discuss how scientists use food webs.
Eating in the Ocean
Imagine that you are a humongous humpback whale. You are very hungry and decide to look for something to eat. You swim far and wide and then you see a part of the ocean that looks red in color.
You instantly swim towards the red water to collect your next meal. As you get closer, you open your large mouth and in flows gallons and gallons of water full of millions of small little creatures called krill. Yum! That was good!Who would have known something so large would eat something so small? I wonder what dolphins, octopus and sharks eat? What about the tiny little krill the whale ate? What do they eat? All of these questions can be answered by a food web.
What Is a Food Web?
A food web is a series of organisms dependent on other organisms for their food sources. An ocean food web is specific for organisms in the ocean. It is kind of like a map.
Instead of telling you how to get to grandma’s house, like a road map, a food web tells you what organisms depend on what other organisms for food. Scientists rely on these types of maps to help them track, collect data and organize the effects that a break in a particular section of the food web would have on an ecosystem. A tuna shortage doesn’t just affect people and sharks, which are the consumers above tuna in a food web. It also affects all of the organisms that the tuna actually feed on as well.
Any time that there is an imbalance in a food web, a whole ecosystem will change.Food webs usually contain multiple food chains. A food web will show how food chains in the web rely on other food chains in or out of the food web to remain capable of producing and consuming the food needed for their chain.
Food chains consist of one single path of relationships between consumers and producers. Consumers in a food chain are any organism that eats or uses another organism. Producers are the organisms (mostly plants) that produce their own food and are eaten by the consumers.
Food Webs & Food Chains
Food webs usually contain multiple food chains. A food web will show how food chains in the web rely on other food chains, in or out of the food web, to remain capable of producing and consuming the food needed for their chain. Food chains consist of one single path of relationships between consumers and producers. Consumers in a food chain are any organism that eats or uses another organism.
Producers are the organisms, mostly plants, that produce their own food and are eaten by the consumers.For example, a food chain for a large shark might look like this, showing a straight line from shark to dolphin to large fish to small fish to krill to phytoplankton:
A food web, however, will consist of multiple paths.
We would see large sharks eating other smaller sharks and fish, like tuna, sun fish and marlin. The smaller sharks will eat tuna, squid and mackerel. Tuna will then eat small organisms like squid and shrimp.
Shrimp will eat very, very small organisms like copepods. Copepods then eat almost microscope organisms, like diatoms and dinoflagellates, which are types of algae, and those algae get their food from the sun. You can see another example of a food web, consisting of multiple food chains below:
An ocean food web could consist of any organism that obtains its food from the ocean or lives in the ocean, like sharks, sea gulls and even humans.
Ocean food webs can include any organism that produces food for ocean residents or that eat ocean residents. Food webs are made of many food chains, which are single paths consisting of both producers and consumers.
Scientists use food webs to determine or predict effects on an ecosystem due to changes in its food web.