Quantcast
Popular

10 Interesting Facts About Earthworms

As winter draws to a close, gardeners begin their spring migration into the outdoors, leaving winter dens behind and coming into contact with the harbingers of the shifting seasons: shovels, hoes and trowels. Oh, and earthworms.


Anyone prone to working the soil knows that upturning the earth exposes these shiny, wigging, pinkish-brownish tubular life forms, sending them thrashing in hasty retreat into the comforting, moist darkness of the soil.

Earthworms: A Garden's Friend of Foe? That depends.

Here are 10 things you may want to know about earthworms:

1. Earthworms come in a seemly infinite variety—around 6,000 species worldwide.

One of the most familiar of them, the sort you may see in your garden, is commonly known as the night crawler (it typically surfaces after dark), the angleworm (its makes popular bait for fishing) or the rain worm (it leaves waterlogged soil after storms).

2. Of the more than 180 earthworm species found in the U.S. and Canada, 60 are invasive species, brought over from the Old World, including the night crawler.

3. Lacking lungs or other specialized respiratory organs, earthworms breathe through their skin.

4. The skin exudes a lubricating fluid that makes moving through underground burrows easier and helps keep skin moist. One Australian species can shoot fluid as far as 12 inches through skin pores.

5. Each earthworm is both male and female, producing both eggs and sperm.

They mate on the surface of the earth, pressing their bodies together and exchanging sperm before separating. Later, the clitellum (a collar-like organ that goes around the worm's body the way a cigar band does a cigar) produces a ring around the worm. As the worm crawls out of the ring, it fills the ring with eggs and sperm. The ring drops off, seals shut at the ends and becomes a cocoon for the developing eggs.

6. Baby worms emerge from the eggs tiny but fully formed. They grow sex organs within the first two or three months of life and reach full size in about a year. They may live up to eight years, though one to two is more likely.

Earthworm egg cases look like tiny lemons. When earthworms hatch, they look like tiny adults. Photo credit: U.S. Department of Agriculture

7. Full size for an earthworm varies among species, ranging from less than half an inch long to nearly 10 feet. The latter monsters don't occur in U.S. backyards—you'll have to go to the Tropics to see one of them. The homegrown versions top out at around 14 inches.

8. The glaciers that crawled across Canada into the northern tier of the lower 48 states during the most recent ice age wiped out earthworms in those areas.

In other parts of the U.S., you may find native earthworm species, but the worms living in the regions scoured by glaciers are invaders from overseas, brought here intentionally by early settlers on the assumption that the worms would improve the soil, or carried accidentally in shipments of plants or even in dirt used as ballast in ships.

9. The earthworm's digestive system is a tube running straight from the mouth, located at the tip of the front end of the body, to the rear of the body, where digested material is passed to the outside. Species vary in what they eat, but by and large their devouring of fallen leaves and/or soil allows the worms to move nutrients such as potassium and nitrogen into the soil.

Also, worm movements within the Earth create burrows that encourage the passage of air and a loosening of the soil. Good things, right? Well, maybe not. Which brings us to 10 ...

10. The northern forest evolved after the glaciers retreated, yielding an ecosystem that does not benefit from earthworms. These forests require a deep layer of slowly decomposing leaves and other organic matter called “duff" that overlays the soil. When earthworms invade these forests, they quickly eat up the duff, with the result that nutrients become less available to young, growing plants and the soil, instead of aerating and loosening, becomes more compact.

The combined effects of such developments have resulted in damage to trees such as sugar maples and to many forest herbs and understory plants, such as trillium, rare goblin ferns, trout lilies and other forest-floor species. In some areas, oak forests have been overrun by buckthorn, and in others the presence of earthworms has allowed the invasion of Japanese barberry.

As duff disappears, so do the insects and other small creatures that depend on it for survival, with the result that animals such as salamanders lose a key food source and face population declines. Earthworm burrows also may speed the passage of water through forest soil, another change that might be a benefit to farmland or a garden with compacted soil but that is a negative in a northern forest.

Earthworm movements within the Earth create burrows that encourage the passage of air and loosening of the soil.

BONUS FACT

Although eradicating earthworms in areas they have already invaded is virtually impossible in practical terms (the measures that wipe out earthworms, such as spraying with pesticides, also kill many other species), we can all help protect as-yet un-invaded ecosystems by keeping worms out of such areas.

If you use earthworms for composting and live in a region near forests that have not been hit by earthworms, you can help by dropping use of the worms. Also, to avoid spreading earthworm eggs when fertilizing with composted materials, freeze your compost for at least a week before using it—freezing will kill eggs as well as the worms.

If you use earthworms for bait fishing, don't dump leftover worms onto the soil at the end of a day's fishing. Remove them from the site, or throw them far enough into a pond that they will die before they can reach to shore. When planting new shrubs or trees in your garden or yard, examine any Earth ball or potting soil for evidence of worms.

Show Comments ()

EcoWatch Daily Newsletter

Sponsored
Health
Pexels

5 Ingredients for Health: Starting with Food

On Food Talk with Dani Nierenberg, Dr. Robert Graham—board-certified physician and founder of FRESHMed NYC—combines mainstream medical practices with therapies inspired by ancient wisdom: an integrative model of medicine. "My dad was a biochemist, so I grew up in this integrative model. One of the things that really stood out is my mom was distrustful about the conventional Western model. She still thinks she's the only doctor in the house, because food is such a powerful medicine, especially from her culture," said Graham.

Keep reading... Show less
Popular
Malte Mueller / Getty Images

When Profit Drives Us, Community Suffers

By David Korten

As I was reading the current series of YES! articles on the mental health crisis, I received an email from Darcia Narvaez, professor of psychology at University of Notre Dame. She was sending me articles being prepared for an anthology she is co-editing with the working title Sustainable Vision.The articles present lessons from indigenous culture that underscore why community is the solution to so much of what currently ails humanity.

Keep reading... Show less
Popular
The Revelator

Interactive Map: Air Pollution in 2100

By Dipika Kadaba

Having a little trouble breathing lately? That's no surprise. Air pollution is already bad in many parts of the country, and climate change is only going to make it worse. Even though many industries are reducing their emissions, a warming climate could actually offset these reductions by intensifying the rates of chemical reactions and accumulation of pollutants in the environment.

Keep reading... Show less
Health
ddukang / iStock / Getty Images Plus

Is Apple Cider Vinegar Good for You? A Doctor Weighs In

By Gabriel Neal

When my brother and I were kids back in the '80s, we loved going to Long John Silver's.

Keep reading... Show less
Sponsored
Animals

Dumpster Debacle Distracts From Serious Spike in Whale Deaths

This week, a video of a failed attempt to put a dead, 4,000-pound whale into a tiny dumpster made the rounds on the internet, garnering chuckles and comparisons to Peter Griffin forklifting and impaling a beached sperm whale on Family Guy.

The juvenile minke whale washed up on Jenness Beach in Rye, New Hampshire on Monday morning, NBC 10 Boston reported. It was found with entanglement wounds, so researchers with the Seacoast Science Center and the National Oceanic and Atmospheric Administration (NOAA) wanted to move the carcass from the beach to a lab for a necropsy to study its death.

Keep reading... Show less
Adventure
Muir Woods, which costs $10 for entry, will have free entry on Sept. 22. m01229 / Flickr / CC BY-NC 2.0

Visit Any National Park for Free This Saturday to Celebrate 25th National Public Lands Day

If you're stuck for plans this weekend, we suggest escaping your city or town for the great outdoors.

This Saturday marks the 25th National Public Lands Day, organized by the National Environmental Education Foundation (NEEF).

Keep reading... Show less
Sponsored
Climate
A glacier flows towards East Antarctica. NASA Goddard Space Flight Center / CC BY 2.0

Temperatures Possible This Century Could Melt Parts of East Antarctic Ice Sheet, Raise Sea Levels 10+ Feet

A section of the East Antarctic Ice Sheet that contains three to four meters (approximately 10 to 13 feet) of potential sea level rise could melt if temperatures rise to just two degrees above pre-industrial levels, a study published in Nature Wednesday found.

Researchers at Imperial College London, the University of Queensland, and other institutions in New Zealand, Japan and Spain looked at marine sediments to assess the behavior of the Wilkes Subglacial Basin during warmer periods of the Pleistocene and found evidence of melting when temperatures in Antarctica were at least two degrees Celsius above pre-industrial levels for periods of 2,500 years or more.

Keep reading... Show less
Energy
Oil well in North Dakota. Tim Evanson / Flickr / CC BY-SA 2.0

Pipeline Leaks 63,840 Gallons of Produced Water in North Dakota

A pipeline released 63,840 gallons (1,520 barrels) of produced water that contaminated rangeland in Dunn County, North Dakota, the Bismarck Tribune reported, citing officials with the North Dakota Department of Health.

Produced water is a byproduct of oil and gas extraction, and can contain drilling chemicals if fracking was used.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!