Science & Nature • Invertebrate

Earthworm

Earthworms are segmented invertebrate worms in the phylum Annelida that live in soil and feed on organic matter.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Earthworms are segmented invertebrate worms in the phylum Annelida that live in soil and feed on organic matter. They are important to soil structure and fertility because they burrow, aerate the ground, and produce nutrient-rich castings. The term covers many species worldwide, including the common earthworm, *Lumbricus terrestris*.

Classification and diversity

Earthworms are invertebrate annelids, most often placed in the class Oligochaeta in older classifications. Sources describe them as a large group with more than 1,800 species, while other references note around 6,000 species worldwide.

Anatomy and biology

Earthworms have segmented, cylindrical bodies and no backbone, lungs, or eyes. They move through soil using body muscles and tiny bristles, and they breathe through moist skin.

Ecological role

Earthworms break down dead organic matter and recycle nutrients into soil. Their tunnels improve soil structure, drainage, and aeration, making them important to many ecosystems and agricultural soils.

Distribution and habitat

Earthworms occur in moist soils in many parts of the world. The common earthworm, *Lumbricus terrestris*, is native to Europe and is now widespread in North America and western Asia.

Human uses and significance

Earthworms are used in composting, fishing bait, and sometimes as feed or food in some regions. Their castings are also used as a natural fertilizer.

Key facts

Earthworms are terrestrial annelids with segmented bodies.
They are detritivores, feeding mainly on decomposing organic material.
Their burrowing helps mix soil, improve drainage, and increase aeration.
Earthworm castings add nutrients to soil and are valued in composting and gardening.
The common earthworm, *Lumbricus terrestris*, is widespread outside its native range in Europe.

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Canadian context

Earthworms are common in Canadian soils and are important to gardening, agriculture, and composting. Some species in Canada and North America are introduced from Europe, which is relevant to soil ecology and land management.

Frequently asked questions

What is an earthworm?

An earthworm is a segmented soil-dwelling invertebrate in the phylum Annelida that feeds on organic matter and helps recycle nutrients in soil.

How do earthworms breathe?

Earthworms breathe through their skin, which must stay moist for gas exchange to work.

Why are earthworms important to soil?

They aerate soil, improve drainage, mix organic matter, and produce nutrient-rich castings that support plant growth.

How many species of earthworms are there?

Sources vary, but one major reference gives more than 1,800 species, while another reports about 6,000 worldwide.

Are earthworms found in Canada?

Yes. Earthworms are present in Canada, and some species in North America were introduced from Europe.

What is the common earthworm?

The common earthworm usually refers to *Lumbricus terrestris*, a widespread species native to Europe.

References

Encyclopaedia Britannica — https://www.britannica.com/animal/earthworm
Supports: Earthworms are terrestrial worms in Annelida; more than 1,800 species; *Lumbricus terrestris* noted as common.
National Geographic — https://www.nationalgeographic.com/animals/invertebrates/facts/common-earthworm
Supports: Common earthworm identity, native range in Europe, soil benefits, and uses in composting and fishing bait.
National Wildlife Federation — https://blog.nwf.org/2014/02/ten-things-to-know-about-earthworms/
Supports: Approximate global species count around 6,000.
National Farmers' Union — https://www.nfuonline.com/updates-and-information/10-top-facts-about-earthworms/
Supports: Soil structure, aeration, drainage, and nutrient movement.