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Build Your Own Food Webs: a creative ecology activity your students will love!

a banner with a picture of animal and plant flashcards on the sidewalk with chalk arrows between them, with the text "science project: let's build a food web! Step-by-step activity directions!"
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Are you searching for an engaging and educational ecology activity to try with your students? Building your own food webs is a fantastic way to study the flow of energy between organisms – all while allowing kids to be creative! Best of all, this is an activity that you can complete outside, making it perfect for homeschool parents and teachers who enjoy having class outdoors! Get ready to inspire your students with this unique and interactive ecology project!

A special note for educators: are you planning to teach this food webs activity? If so, I’ve already created all the worksheets, printable materials, handouts, and directions that you will need. Find these materials in my complete Food Webs Unit โ€“ and you’ll support this blog with your purchase! ๐Ÿ’š

What is a food web?

A food web is a complex network of feeding relationships between organisms in an ecosystem. Energy flows from the organism being eaten to the organism doing the eating. We represent food webs using diagrams with arrows between the organisms. Food web diagrams map the many paths for the movement of energy between organisms.

I wrote a separate blog post in which you and your students can read more about food webs and food chains. It includes lots of diagrams and examples!

What types of organisms make a food web?

Flashcards of animals, plants, and fungi sorted into piles labeled consumers, producers, and decomposers

All the different lifeforms coexisting in an ecosystem form a community. The community is made of many individual, diverse lifeforms – like plants, animals, and fungi – called organisms.

When you build your food web model, it will include many different types of organisms. These organisms fall into three main categories, based on the roles they play in the food web. Knowing the difference between these roles will help you and your students build food webs.

In an ecosystem, you will find the following types of organisms:

1. Producer:

An organism that produces its own food through photosynthesis. Producers use sunlight, water, and carbon dioxide to make their own food. They also need soil nutrients.

Examples: trees and other plants, some plankton, moss, some microorganisms

2. Consumer:

An organism that eats other organisms as food. Consumers cannot make their own food. Consumers can be herbivores, omnivores, carnivores, and scavengers.

Examples: insects, birds, frogs, deer, other animals

3. Decomposer:

An organism that recycles nutrients back into the soil by eating and digesting decayed plant and animal matter and waste.

Examples: mushrooms, some worms, soil bacteria

Make your own food webs activity:

Gather your materials and follow these steps to create your own food webs with your students. You can all work on one big food web together, or each student can make their own mini-food web! There are many possibilities!

Materials

  • Flashcards or pictures of the organisms in an ecosystem (plants, animals, fungi, etc…)
    • Find an easy-to-use set in my food webs unit
    • Or, get a set for an ecosystem of interest (e.g., desert, arctic, forest, etc…)
    • You can also make your own set!
  • Sidewalk chalk
  • A large, paved area outdoors that is free of cars and heavy foot traffic

Step-by-Step Directions

Set-Up:
  1. Sort the organism cards into 3 piles:
    • producers
    • consumers
    • decomposers
  2. Look through your producers pile.
    • This pile represents the food sources for herbivores and omnivores (primary consumers) in your ecosystem.
  3. Look through the consumers pile.
    • Sort these cards further or make a mental note of which organisms are likely to eat plants (herbivores and omnivores) and which organisms are likely to eat animals (carnivores and omnivores).
  4. Research the diets of unfamiliar animals.
    • If students are unfamiliar with some of the animals and their diets, it may help to research the animals online. You can take notes on the backs of the cards if needed.
    • Note: if you’re using my food webs unit, a handout is provided with info on the diets of the included animals!
Build Your Food Web:
  1. Choose your producers.
    • It is easiest to start with one to three producers.
  2. Which consumers eat your producers? These are your primary consumers.
    • Place the primary consumers above your producers and draw arrows to represent the flow of energy from food to eater.
  3. Which consumers eat your primary consumers? These are your secondary consumers.
    • Place the secondary consumers above your primary consumers and draw arrows to represent the flow of energy from food to eater.
  4. Which consumers eat your secondary consumers? These are your tertiary consumers.
    • Place the tertiary consumers above your secondary consumers and draw arrows to represent the flow of energy from food to eater.
  5. Repeat this process as needed, until your reach a consumer that is not eaten by anyone else – this is your top predator!
    • You can make your food web as big or small as you’d like! It could include dozens of organisms or just a few.
  6. Add additional arrows as needed.
    • Food webs can be messy! Many any animals have multiple food sources and are preyed on by multiple predators.
  7. Optional: place any decomposer cards underneath the food web. Decomposers recycle nutrients back into the soil to help producers like plants grow!

Example Food Webs:

A food web made from printed pictures of animals and plants connected with arrows drawn with sidewalk chalk on a sidewalk
An example of building your own food web!

Study Food Webs with Wild Earth Lab:

Of course, you can put together your own food web materials to complete this activity. Or, save time and support my blog when you purchase my food webs unit! The unit includes everything you need to complete this activity plus additional handouts, worksheets, and readings!

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love using my other environmental science materials in your classroom!


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Aquatic Ecosystems: How to tell if a pond, stream, or wetland is healthy

a banner with a photo of a stream

This is part 2 of a two-part post on aquatic ecosystems. If you haven’t already, check out part 1!

In a rush? Click here to go straight to the printable scavenger hunt!

In my last post, I shared my experience working as a science technician studying aquatic ecosystems like streams, ponds, and wetlands. These water features are critically important to many ecosystems and the creatures that live there. They also provide us with a lens through which we can glimpse the overall health of an ecosystem. In this post, I’ll teach you some signs to look for to recognize healthy aquatic ecosystems in your area. How do your local ponds, streams, and wetlands measure up?

Watkin’s Glen in New York state is home to some incredible water features and lush vegetation

Free of Trash

This one seems obvious, but it is worth including first because of how important it is, and because it is something we can all help prevent and fix. Litter and trash can be harmful to wildlife and plants. Lots of trash floating on the surface of water can impact the amount of light and oxygen in a pond or stream. Below the waterโ€™s surface, aquatic plants need sunlight and oxygen for photosynthesis, the process through which plants make their own food. Furthermore, our trash, especially plastics, contains harmful chemicals that may harm aquatic animals. Animals like fish, birds, and turtles confuse trash for food and eat it, which can be very toxic to them. Healthy aquatic ecosystems should be free of human trash.

Diverse Plant Communities

Any time you see an area dominated by just one plant, that might be a clue that something is wrong. Unhealthy ecosystems are more susceptible to invasive plant species. When an invasive plant species is introduced to an ecosystem, it can outcompete native plant species. Where there were once many diverse plant species, a single invasive plant may take over. This will send ripple effects through the whole local food chain. Examples of invasive plants species in North America include cheat grass, kudzu, garlic mustard, and buckthorn trees.

The Poudre River in Northern Colorado is an example of an ecosystem impacted by an invasive plant. Invasive cheat grass is found along its floodplain in some areas.

Some Algae, but not Too Much

It is natural for stagnant bodies of water (non moving bodies of water like ponds and wetlands), and slower moving streams to have a good bit of algae. Fish, aquatic insects, and other invertebrates need algae as a source of food. But how much is too much? When ponds are near farm fields, the runoff into them may contain too much of the nutrients phosphorous and nitrogen, which is found in many fertilizers. After rain, water flowing off of farm fields and lawns will wash fertilizers containing phosphorous, nitrogen, and other chemicals into low-lying ponds and wetlands. This can cause massive, unnatural plumes of algae to form, which block out sunlight, deplete oxygen, and make it difficult for any other life forms to survive in the pond. When one species takes over, such as a massive plume of algae, it is often a sign that something is out of balance in an ecosystem.

A remote pond below Vestal and Arrow Peaks near Silverton, Colorado, in the San Juan Mountains contains clear water with a small amount of algae.

Abundant and Diverse Aquatic Macroinvertebrates

Have you ever flipped over a rock in a pond or stream? Chances are you saw tons of wriggling little creatures underneath! These creatures are aquatic insect larvae, such as mayflies, dragonflies, and caddisflies (โ€œcase-makersโ€) and other aquatic macroinvertebrates! “Aquatic macroinvertebrates” is a general word for tiny creatures with no backbones that live in water. They include insect larvae, worms, snails, crayfish, and more. Many aquatic macroinvertebrates are herbivores of algae and provide an important food source for many fish species.  A healthy ecosystem should have a variety of different aquatic macroinvertebrates!

Many macroinvertebrate species are sensitive to disturbances and contaminants in an ecosystem, so their populations will reflect an ecosystem’s health. The aquatic macroinvertebrates in a pond or stream are actually such an excellent indicator of ecosystem health that scientists routinely use studies of the aquatic macroinvertebrates in a stream or pond as a holistic measure of aquatic ecosystem health! A healthy aquatic community will have abundant and diverse macroinvertebrates.

This is me, collecting aquatic insects from a lake while I was an undergraduate in college. Using a mesh net and a pan, I found all sorts of benthic macroinvertebrates, including stonefly larvae, caddisfly larvae, and mayfly larvae.

Multiple Trophic Levels

A healthy ecosystem should also contain a variety of different living things including plants, herbivores, predators, and decomposers. These life forms represent different trophic levels, or positions in the food chain, and all play different roles in the ecosystem to maintain balance. A classic example is the relationship between wolves, elk, and riparian plants. When an ecosystem is healthy, all three thrive. However, if wolves (or other top predators) are driven out of an area, the elk population will increase since no one is eating them any more. That will cause the plant populations to suffer, because more elk eat more plants. Additionally, without fear of predation, herbivores like elk will be emboldened to graze out in the open near wetlands and streams, rather than hiding in the woods. This leads to greater stress on the plants around aquatic ecosystems.

Scientists study this effect by building fences around small areas of an ecosystem, to keep out elk, and to see what an area would look like without exaggerated grazing. This same sort of imbalance between plants, herbivores, and predators can happen on a smaller scale too. In some pond ecosystems, the top predators (predators that are not prey to any other animals) might be herons, hawks, or otters, rather than wolves. See if you can identify a top predator in a local pond or stream ecosystem near you. In a healthy ecosystem, look for a variety of insects, fish, birds, amphibians, and other animals.

A bald eagle, a top predator, perches overlooking the Wisconsin river
Many turtles are omnivores that eat a variety of both plant and animal foods

Free of Chemicals

Chemicals can get washed into water from surrounding human settlements and agriculture. Some chemicals might be noticeable, and appear as a white or yellow froth on top of water, an oily sheen floating on the surface, or an unnatural metallic or rusty color. Some chemical pollutants are invisible, but their impact on wildlife is not! For example, road salts, when dissolved in water might be invisible, but it can impact the number of female frogs that are born in a pond – which can impact a frog species’ ability to reproduce.

Another example of a harmful but nearly invisible chemical is a mosquito pesticide called DDT. When DDT gets into pond and stream water, it accumulates in the tissues of plants. These contaminated plants are eaten by macroinvertebrates and small fish, which are in turn eaten by larger fish, which are eaten by raptors like bald eagles. On each step up the food chain, the amount of the DDT chemical would build up in the organisms, in an effect called biomagnification. The bioaccumulated DDT in the eagles caused the shells of the eggs they laid to be too weak, which caused an enormous threat to this species. Luckily a biologist named Rachel Carson figured out the cause of the problem and DDT was later banned in the United States. DDT is still legal in some countries.

Healthy Soils

We love visiting streams and wetlands, but too many human or livestock visitors traveling over fragile surfaces can have a big impact. Human visitors and livestock that are not natural to an area can cause soil compaction by repeatedly walking over the same area, this can make it very difficult for plants to grow. Plants are an important part of a pond or stream ecosystem because their roots help stabilize the banks or shores, preventing erosion. Signs of excessive erosion like undercut banks and over compacted, plant-less soil can be signs that an ecosystem isnโ€™t doing so well. Water also cannot infiltrate into soils as easily when they are too compacted – which may cause floodwaters to pool rather than seep back into the ground. To help prevent impacts to soils, you can stay on designated trails and recreation areas when visiting a local stream, pond, or wetland.

Spring Creek in Fort Collins, Colorado. A corridor of grassy, natural areas along the creek’s floodplain provide an area to accommodate floodwaters and promote water infiltration into the soils.

Ways we can all help promote healthy aquatic ecosystems!

  1. Stay on trails, boardwalks, and already-impacted surfaces when visiting local streams, ponds, and wetlands.
  2. Pack out your trash or dispose of it properly in a trash can or dumpster.
  3. Consider bringing an extra baggie or container on hikes to pick up litter.
  4. Help prevent the spread of invasive plant species by checking your shoes and clothing for burs, seeds, or other plant materials.
  5. Help prevent the spread of invasive animal species by not releasing aquatic pets into local ecosystems.
  6. Consider reducing the amount of chemicals you use in your lawn or garden to prevent chemical run-off into nearby wetlands, ponds, or streams. More about this in my post on improving you backyard wildlife habitat, if you haven’t read it yet!
  7. Consider joining a volunteer group in your area that helps pull up invasive plant species in parks and on public lands.
  8. Teach your family about healthy aquatic ecosystems. I’ve made a free aquatic ecosystem scavenger hunt for you to download, shown at the bottom of this page! Or purchase my Pond Ecology Unit – which includes activities, flashcards, and posters for learning about ecosystems!
Boardwalks provide a route for visitors to cross fragile riparian areas while minimizing impacts to plants and soils

Are you interested in learning more about ecosystems and conservation? Subscribe at the bottom of this page, or follow Wild Earth Lab using the links below!


Can you spot the signs of a healthy aquatic ecosystem at a pond near you? Download this free learning poster!

Want more printable nature learning activities? Visit the free learning resources page and my Etsy Shop!


References and Further Reading

  1. Dennehy, K. (2016). Road salt can change sex ratios in frog populations, study says. Yale News. Available: https://news.yale.edu/2016/11/22/road-salt-can-change-sex-ratios-frog-populations-study-says
  2. Environmental Protection Agency. (2020). Impacts of Mismanaged Trash. Available: https://www.epa.gov/trash-free-waters/impacts-mismanaged-trash
  3. Environmental Protection Agency. (2016). Indicators: Benthic Macroinvertebrates. Available: https://www.epa.gov/trash-free-waters/impacts-mismanaged-trash
  4. Frey, D. (2018). Study shows Yellowstone wolvesโ€™ impact on streams. The Wildlife Society. Available: https://wildlife.org/study-shows-yellowstone-wolves-impact-on-streams/
  5. National Ocean Service. (n.d.). What is nutrient pollution? Available: https://oceanservice.noaa.gov/facts/nutpollution.html
  6. National Park Service. (2017). Elk and moose exclusion fence. Available: https://www.nps.gov/articles/elk-and-moose-exclusion-fence.htm
  7. Natural Resource Defense Council. (2015). The Story of Silent Spring. Available: https://www.nrdc.org/stories/story-silent-spring
  8. U.S. Fish and Wildlife Service. (2019). Midwest Region – Bald and Golden Eagles Fact Sheet. Available: https://www.fws.gov/midwest/eagle/Nhistory/biologue.html

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