Are Earthworms native to North America? The Surprising Truth

Earthworms – those wiggly, squirmy denizens of the soil – are a familiar sight across North America today. But are they actually native to this continent? Or are they invasive interlopers that hitched a ride from elsewhere? As a leading wormologist, I’m here to dig into the mysterious origins of earthworms in North America.

are earthworms native to north america

The Common Earthworm – An Introduced Species?

Many of the earthworms found in North American soils are from the common genus Lumbricus, including the nightcrawler (L. terrestris) and the smaller red worm (L. rubellus). For years, scientists assumed these worms were native species that had always been present.

But in the 1980s, startling evidence emerged that challenged that assumption. Through analysis of fossil records and Native American land management practices, researchers realized that Lumbricus earthworms were nowhere to be found in North America prior to European settlement!

So how did these humble invertebrates make their way across the Atlantic? Read on to uncover the surprising secrets of…

The Earthworm Invasion!

It turns out the Lumbricus earthworms so abundant in North America today likely hitched a ride with early European settlers. Rich forest soils in northern Europe were teeming with these earthworms, which burrowed into the root balls of seedlings and stowawayed in the cargo holds of ships sailing for the New World.

Once here, they spread quickly across the continent:

  • In the soil – Earthworms can travel underground, burrowing through soils at rates of up to 30 feet per year!
  • On animals – Earthworm cocoons can stick to the feathers of birds or the fur of mammals, allowing them to hitchhike to new areas.
  • In materials – Cocoons and adult worms can survive in soil-containing materials like agricultural products or building materials. Early railroads and canals aided their spread.

The end result? Earthworm-free landscapes quickly became dominated by these voracious invertebrates!

Earthworms Impacts on North American Ecosystems

The introduction of European earthworms has had dramatic impacts on North American soils and ecosystems:

  • Loss of forest floor – The forest floor in worm-free northern forests built up thick layers of organic matter. With earthworm invasion, those layers are consumed, stripped down to the bare mineral soil.
  • Changed nutrient cycles – Earthworms accelerate breakdown of organic matter and nutrient cycling. This can leach nutrients from the soil, depleting food sources for plants.
  • SHIFT IN UNDERSTORY – Loss of the forest floor and changed nutrient levels tend to favor certain fast-growing understory plants like ferns and grasses, while suppressing other native plants.
  • Erosion problems – With the spongy forest floor removed, mineral soils are more exposed to erosion from wind, rain, and runoff.

Clearly, the humble earthworm has dramatically reshaped ecology across much of North America!

The Takeaway: Earthworms as Invasive Species

  • Common earthworms like the nightcrawler are not native to North America – they were likely brought over by early European settlers.
  • Lacking natural predators, they spread quickly across the continent.
  • Their consumption of the forest floor and burrowing activity has significantly changed North American ecosystem structure and function.
  • But in a managed garden, their services like organic matter breakdown and soil improvement can be very beneficial.

The lowly earthworm has a complex environmental legacy – vilified invader in some contexts, yet valued soil builder in others. Their story reminds us that species introductions can have far-reaching and often unexpected ecological consequences.

So next time you unearth one of these squirmy creatures, take a moment to appreciate both their natural wonder and the outsized ecological shadow they cast! The earthworm’s tale still has dirt left to uncover, and I for one can’t wait to see what other surprises may yet wriggle to the surface.

FAQs about earthworms native to north america

How did earthworms get to North America?

Earthworms arrived in North America primarily through human activity, including European colonization and the importation of plants and soil containing earthworm eggs or cocoons.

When did earthworms come to North America?

Earthworms came to North America primarily during European colonization, with documented introductions dating back to the 1600s and 1700s.

Are there any native earthworms in North America?

Native earthworms once inhabited North America before the last ice age, but the majority of earthworm species found today are non-native, introduced species brought over by European settlers.

Did Europeans bring earthworms to America?

Yes, Europeans inadvertently brought earthworms to America through their colonization efforts, unintentionally introducing various earthworm species to the continent.

Are earthworms invasive to North America?

Some earthworm species introduced to North America have become invasive, altering soil structure and nutrient cycling in ways that can negatively impact native ecosystems.

Also, Read More About – How Long do Earthworms Live?

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