Harm to food chains and food webs
This Topic is About...
- I will learn that some substances can harm living things, and that these substances can move through a food chain or food web.
- I will play a game to show how harmful substances can move through a food chain or food web.
- I will explain how a game can show the way harmful substances can move through a food chain or food web.
- I will record results in a table, draw a graph, and describe a pattern in the results.
- I will research information to answer questions about a harmful substance in food chains.
Key Words
- accumulate
- environment
- microplastics
- pesticides
- toxic
Tap to Learn the Meanings!
- accumulate: To gather or build up over time.
- environment: Everything around us, including air, water, and land.
- microplastics: Tiny pieces of plastic that come from larger plastic objects.
- pesticides: Chemicals used to kill insects or pests that harm plants.
- toxic: Something that is harmful or poisonous to living things.
Great job learning new science words!
Understanding the Environment
FThe environment is everything around us. It includes air, water, soil, and other living things. Some substances in the environment can be harmful or toxic to living things. These substances include certain metals, such as mercury and cadmium.
Microplastics and Toxicity
Very small particles of plastic called microplastics can also be toxic, especially in ocean food chains and food webs.
Harmful Substances in the Environment
People put harmful substances into the environment, sometimes by accident and sometimes on purpose. For example, farmers and gardeners don’t like insects, snails, worms, and other pests that eat their plants. They often use chemicals called pesticides to get rid of the pests. Pesticides are another type of harmful substance that can affect food chains.
The Effect of Pesticides
If a farmer sprays a pesticide on his or her crops, the pest that eats the crop will die. Pesticides can also kill consumers in a food web that are not pests. For example, butterflies can die if they drink nectar from a flower sprayed with a pesticide.
Predator and Prey in Food Chains
Other living things in a food chain or food web can also be affected by pesticides. For example, a bird may eat a snail that was killed by a pesticide. The pesticide enters the bird’s body. The bird may not die, but the pesticide could affect it in other ways. For example, the bird’s bones may get weaker. A predator that eats the bird will also take in any pesticide still in the bird’s body.
Harmful Substances in the Environment
People put harmful substances into the environment, sometimes by accident and sometimes on purpose. For example, farmers and gardeners don’t like insects, snails, worms, and other pests that eat their plants. They often use chemicals called pesticides to get rid of the pests. Pesticides are another type of harmful substance that can affect food chains.
The Effect of Pesticides
If a farmer sprays a pesticide on his or her crops, the pest that eats the crop will die. Pesticides can also kill consumers in a food web that are not pests. For example, butterflies can die if they drink nectar from a flower sprayed with a pesticide.
Predator and Prey in Food Chains
Other living things in a food chain or food web can also be affected by pesticides. For example, a bird may eat a snail that was killed by a pesticide. The pesticide enters the bird’s body. The bird may not die, but the pesticide could affect it in other ways. For example, the bird’s bones may get weaker. A predator that eats the bird will also take in any pesticide still in the bird’s body.
FUN QUESTIONS
1. How does the pesticide get into the food chain in the picture?
Show me!
2. How does the pesticide move through the food chain?
Show me!
3. Redraw the food chain to show how the pesticide could be passed to people.
Show me!
Toxic Substances in the Environment
Some toxic substances will break down into other harmless substances in the soil or water in the environment. Others stay in the environment and do not break down. These substances build up or accumulate in food chains. They can harm the organisms in the food chain, especially the predators at the end of the chain.
Example of Pesticide Accumulation
For example, a pesticide is sprayed on a plant. A bug eats the plant, which contains 5 units of pesticide. A lizard eats 3 bugs, each containing 5 units of pesticide, so it consumes 15 units of pesticide. Then, an eagle eats 2 lizards, consuming 30 units of pesticide. The pesticide can make the eagle's eggshells weak and crack.
Let’s Investigate!
Question: How do toxic substances, like pesticides, move through food chains?
Equipment:
- Paper cups marked with different colors
- Paper pesticide 'particles'
- Sticky notes
Method:
- Group into rice plants, caterpillars, frogs, and kingfishers.
- Start the game by collecting 'rice pesticide particles' into your cups.
- Tag others with sticky notes and collect their pesticide particles.
- Draw a table and record your results.
- Draw a bar graph to show the number of pesticide particles in each living thing in the food chain.
Follow-up Questions:
Tap to See Answers
- 1: The rice plants represent the producers in the game.
- 2: The caterpillars represent the first consumers in the food chain.
- 3: The frogs represent the second consumers in the food chain.
- 4: The game shows how pesticides move from plants to consumers and predators through the food chain. Great work!