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Cool Critter: The Humble Earthworm

October 17, 2008

Earthworms are a little different from our previous cool critters. Biologically speaking, they’re not cool at all. They’re worms, for God’s sake. Basically, earthworms are tubes. They eat and poop. Even earthworm sex is boring (shocking, I know). They are hermaphrodites that get together every once in a while to exchange sperm. They store the sperm and eventually create a cocoon into which they inject their eggs and the other worm’s sperm.

So how, pray tell, did earthworms make the cut as a cool critter? Just check out what these appendage-less wonders can do.

As you probably know, earthworms are a gardener’s little helper. They aerate, mix and fertilize garden soil just by doing their earthworm thing (ie. tunneling, eating and pooping). In the garden, they eat organic material at the surface and mix it with the mineral-rich soil underground in the form of poop. (Vermiculture-worm-assisted composting-works the same way.)

But when the little goody-goodies try this sh*t in the forest it doesn’t go over so well, partly because they’re not supposed to be there. Wait, what? Yeah, most earthworms in the U.S in Canada didn’t make it through the last ice age. But when settlers arrived, they brought plants and soil (and worms) to cities and farms. It wasn’t until recently when fisherfolk started dumping their leftover bait worms in the woods (as they were told to do) that worm sightings became more common in the northern forests. 

So what’s the big deal with forests? Worms do their worm thing-eat the decomposing organic matter on the forest floor-but forest soil doesn’t need any wormy assistance. In fact, native plants and tree seedlings depend on that layer of duff (the decomposing organic matter) to support their roots. When worms eat the duff, the native plants have nowhere to grow, but invasive plants thrive.

Recent research shows that earthworms do more than eat, poop and burrow. The little bastards also plant ragweed seeds. (Ragweed is a major allergen and a weed that plagues corn and soybean fields in the Midwest.) By tying strings to ragweed seeds placed near worms’ burrows, scientists observed that the worms collected more than 90% of the seeds and carried them into their burrows, one at a time. (Isn’t research fantastic?) The scientists found six times more ragweed seeds in the worms’ burrows than the surrounding soil. They also found that the seeds the worms buried grew into the healthiest plants.

The researchers don’t know why the worms collect the seeds, but the consequences are pretty clear-the worms protect the seeds from becoming bird, beetle and rodent food and somehow help the plants thrive. So when you’re miserably sneezy next August, thank a freakin’ earthworm.

Really, they’re not all that bad. Perhaps the coolest thing some earthworms do is clean up toxic waste. (Don’t try this at home, no matter how bad your allergies are.) Scientists in the UK have discovered newly evolved superworms that eat lead, zinc, arsenic and copper. It’s impressive enough that the worms can survive eating these heavy metals, but what’s even cooler is that they process them into slightly different forms that plants can suck up. Once the plants have pulled the superworm-processed metals out of the ground, yanking the plants out of the soil should reduce the soil’s toxicity…or that’s the idea, anyway.

But THE coolest thing about earthworms isn’t the worms at all. It’s worm grunting, a technique bait catchers use to snag worms. They run a piece of iron across a stake in the ground to create a grunting sound that mimics the sound of a burrowing mole. Seconds after the grunting begins, worms pour out of the ground. Don’t believe us? Check out this video from the 2008 Sopchoppy Worm Grunting Festival.

3 Comments leave one →
  1. January 2, 2009 6:32 pm

    An earthworm can produce their own weight in castings every 24 hours that is 1/3 pound of fertilizer a year!

  2. January 2, 2009 6:34 pm

    Worm Composters


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