Rainforests are often called the lungs of the Earth. Wetlands do something just as vital, closer to a kidney’s job.
🏛️ Must Know
Why Wetlands Get Called Earth’s Kidneys
- Aquatic Plants Filter Pollutants Aquatic plants in wetlands absorb heavy metals and excess nutrients from water. This is the function that best matches the “kidney” comparison.
- Not the Water Cycle Function The water cycle in wetlands (runoff, percolation, evaporation) describes hydrology, not filtration, so it doesn’t match the kidney analogy.
- Not the Food Web Function Algae forming the base of a food web describes ecology, not purification, so it also doesn’t match.
Good to Know
📘 Good to Know
How Wetlands Actually Clean Water
- Denitrification Microbes in wetland soil convert excess nitrogen into harmless nitrogen gas, a process called denitrification.
- Real Plants Doing Real Work Species like water hyacinth and Hydrilla verticillata have been used specifically to remove heavy metals from wastewater.
- Not Just Sediment Control Sedimentation balance and soil stabilization are real wetland functions too, but they describe a different job than filtration.
📝 Previous Year Questions
UPSC CSP 2022 — Which Function Matches the Kidney Analogy
- UPSC 2022 Aquatic plants absorbing heavy metals and excess nutrients best reflects wetlands’ “kidney” role, filtering pollutants the way kidneys filter blood. See UPSC CSP 2022 GS Paper I, Q43. View this question.
Test Yourself
Great to Know
🌟 Great to Know
Why This Filtration Role Matters for Policy
- Protects Downstream Water Quality A healthy wetland upstream can measurably improve the water quality of the river or lake it feeds into.
- A Reason to Protect Ramsar Sites This filtration function is one reason India designates and protects wetlands as Ramsar sites, alongside their biodiversity value.
- Connects to Other PYQ Facts This same “wetlands as natural infrastructure” framing recurs in UPSC questions on flood control and groundwater recharge.
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