Indicator Species ID
Some living things only survive in clean conditions, and others thrive in dirty ones. Learn to read the water and the air by the species you find in them.
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Indicator Species ID 🐛
You do not always need a machine to spot pollution. Some living things, called **indicator species**, reveal the state of the environment just by being there, or by being absent. Because some organisms only survive in clean conditions while others tolerate dirty ones, a quick look at what lives in a river, or on a tree, tells you a lot. (Higher tier.)
Reading the water 🌊
The animals living in a river reveal how clean or polluted its water is: - **Bloodworms** and **sludgeworms** can survive in **polluted**, low-oxygen water, so finding them suggests pollution. - **Freshwater shrimp** and **stonefly larvae** need **clean**, oxygen-rich water, so finding them suggests the water is clean.
Match each species to what it indicates
- Bloodworm or sludgeworm
- Freshwater shrimp or stonefly larva
- Lots of lichen on trees
- Bare trees with no lichen
- Polluted, low-oxygen water
- Clean, oxygen-rich water
- Clean air, low in sulfur dioxide
- Polluted air, high in sulfur dioxide
On a field survey
An interactive activity.
Reading the air 🌫️
Two organisms reveal air quality, and both are sensitive to the pollutant **sulfur dioxide**: - **Lichens** grow well only in clean air. Lots of lichen (especially bushy, leafy kinds) means clean air; bare trees mean the air is polluted. - **Blackspot fungus** on rose leaves also needs clean air. So finding blackspot fungus means the air is clean, while its absence suggests sulfur dioxide pollution.
What does it mean?
Blackspot fungus grows on rose leaves only where the air is low in sulfur dioxide. What does finding blackspot fungus tell you about the air?
- The air is clean, with little sulfur dioxide
- The air is polluted with sulfur dioxide
- Only that the roses are diseased by pollution
- Nothing at all about air quality
Reading the signs
Select ALL THREE statements about indicator species that are TRUE.
- Bloodworms indicate polluted water
- Plenty of lichen indicates clean air
- Indicator species are a cheap way to monitor pollution
- Stonefly larvae indicate polluted water
- Lichen thrives where sulfur dioxide is high
- Indicator species give an exact numerical measurement
Why bother?
What is the main advantage of using indicator species to monitor pollution, rather than electronic sensors?
- They are cheap and simple, giving a quick biological indication
- They give a more precise number than any sensor
- They work even where nothing is living
- They remove the pollution as they measure it
Indicator summary
Indicator species reveal pollution by where they live. Bloodworms and sludgeworms are found in _____ water, while shrimp and stonefly larvae need _____ water. Plenty of _____ on trees shows the air is clean, because it is sensitive to _____ dioxide.