Earthworms do not have lungs. They breathe through their skin.
Why Earthworms Don't Need Lungs
Earthworms belong to the phylum Annelida, which includes segmented worms. Their respiratory system differs significantly from that of mammals, birds, or even amphibians that utilize lungs. Instead of lungs, earthworms rely on a process called cutaneous respiration:
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Cutaneous Respiration: This means they breathe directly through their skin. Oxygen diffuses across their moist skin and into their bloodstream, while carbon dioxide diffuses out.
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Moist Skin is Crucial: Earthworms' skin must remain moist for efficient gas exchange. This is why they typically live in damp environments.
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Circulatory System: Earthworms have a closed circulatory system that helps transport oxygen throughout their body.
Examples of Animals With and Without Lungs
| Animal | Respiratory System |
|---|---|
| Earthworm | Skin (cutaneous) |
| Human | Lungs |
| Fish | Gills (usually) |
| Frog | Lungs and Skin |
| Insects | Tracheal tubes |
Amphibians and Respiration
While some amphibians primarily use lungs, others, particularly in their larval stage (like tadpoles), use gills. Many adult amphibians supplement lung breathing with cutaneous respiration.
