How do composting worms move without legs? Worms move toward food and safety. They move away from light and danger. They dig tunnels. The best worms for composting are Red Wigglers. Super Reds are for composting or releasing into the soil. These ancient creatures have been moving on and through the earth for many millions of years. What method of propulsion do they use?
Anatomy
Earthworms are members of the phylum Annelida. The word is Latin, meaning “little rings.” Worms have small rings around them called “segments.” The segments are essential to worm movement.
Most of the segments have eight tiny bristles called “setae” around them. When extended, these bristles grip the soil. The worm can retract or extend the bristles at will.
Only the very first and last segments do not have setae. The head segment usually leads the way, but worms can move backward if they want. Food and soil go into the mouth in the head segment. Worm castings (poop) come out the last segment of the worm. Worm castings contain valuable nutrients and soil-friendly bacteria that enrich the soil.
Worms are invertebrates, literally meaning that they have no backbone. They have no bones at all, which helps them squeeze into tight spaces and around corners uninhibited. They make tunnels by eating soil and organic matter. As they move through the soil, they secrete slippery mucus from their skins. The mucus stabilizes the tunnels. Worm tunnels are crucial for bringing air, water, and nutrients deep into the soil.
How Composting Worms Move
Composting worms move by expanding and contracting muscles. They have circular muscles around each segment. Also, they have muscles along their length. Contracting the circular muscles makes the earthworm stretch out. Contracting the longitudinal muscles makes the worms shorter. An earthworm moves like this:
- The worm reaches forward by contracting the circular muscles in the front part of its body. It becomes thinner and longer.
- It grips the soil by extending its tiny bristles (setae) in the front of its body.
- The worm contracts the longitudinal muscles. The earthworm gets wider and shorter, or it curves its body. This pulls the back part of the body forward. The worm has now moved its entire body forward.
- It grips the ground using the setae on the back part of its body and repeats from Step 1.
How Worms Navigate
Worms have limited senses compared to ours. They do not have eyes, noses, or appendages. However, they have several ways of navigating their surroundings.
The worm’s head has an organ called the “prostomium.” This small lobe, located above the mouth, looks similar to a lip. The prostomium helps the worm feel its way around.
Their skin provides additional sensory data. Light-sensitive cells are distributed throughout its skin, especially at the ends of the worms. They can detect both the presence of light and its intensity. Worms prefer the dark, so they move away from light.
Worms have sensitive skin. Contaminants such as shredded bleached office paper irritate their skin. They can detect temperature. They try to find locations with enough air and moisture. If they get too wet or too dry, they can get sick or die. They can feel vibrations, too.
In the Bin
Snug in a composting bin, worms do what comes naturally. They use their muscles and setae to move around. They dig tunnels, making the bedding fluffy. And they excrete worm castings, providing fertilizer for your plants. When you open the bin and shine a light, worms dig down to get away. They naturally seek out comfy spots in the bin where there is food, enough moisture, and air. All you must do is provide a bin, bedding, kitchen scraps, and a safe location. Protect them from extreme cold and extreme heat, and they will work hard for you!
Uncle Jim’s Worm Farm has been producing worms for more than 40 years. Check out our website for Red Wiggler Mix, Super Reds (European Night Crawlers), indoor composters, and supplies.
One comment on “How Do Composting Worms Move?”
BY MATTHEW L. MILLER
APRIL 15, 2019 Follow Matthew
earthworm in soil
An earthworm in the soil. Photo © Dan Brekke / Flickr
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I spent much of my walk across town this morning dodging earthworms. It has rained much of the past 24 hours, and the worms were everywhere. On the sidewalk, in puddles, on the street.
Many of us have seen so many earthworms emerging after rainstorms that we don’t pay much attention. Even the most curious urban naturalist probably doesn’t think about it much, because we already assume we know what’s going on. It is probably one of the first “nature lessons” we learned at school: earthworms have to come to the surface after rain because they’re drowning.
As is the case with so many nature stories, the real reason is likely more complicated than we imagine. Let’s dig deep, if you’ll pardon the pun, and look at what’s really happening when we see earthworms on a soggy sidewalk.
The Truth About Drowning Worms
Conventional wisdom holds that earthworms head to the surface after rain because they can’t breathe. This is still taught to schoolkids, and you can find a lot of detailed explanation online. Most claim that worm trails and air pockets underground become submerged, and the earthworms can’t breathe. It makes sense.
Most researchers, though, dispute this explanation. As Chris Lowe, a researcher at the University of Central Lancashire, points out in Scientific American, earthworms breathe through their skin and require moisture to do so.
Humans drown when their lungs fill with water. This is not possible for earthworms as they lack lungs. Multiple studies have also shown that most earthworm species can survive being submerged in water for two weeks or more.
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Lately, most popular scientific accounts write off the “drowning worm” idea as a myth. While it is certainly not likely the entire explanation, perhaps we shouldn’t entirely rule it out. Research published in the journal Invertebrate Biology, for instance, found that worm behavior following rain depended on the species.
Two earthworm species with different life histories were investigated by the Taiwanese researchers. One species consumed more oxygen at night than during the day, and the other consumed lower amounts of oxygen equally during a 24-hour period.
The species that consumed more oxygen at night tolerated water immersion poorly. At night, when it needed oxygen the most, it was especially intolerant of rainfall and came to the surface.
The other species never came to the surface, even during the rain. Its consistent, lower intake of oxygen enabled it to better stand water immersion.
So it may well be that the earthworms you see on sidewalks and streets are those that need more oxygen. But many researchers doubt this is the entire explanation.
earthworm
An earthworm. Photo © fir0002 / Wikimedia Commons
Raindrops Sound Like…Moles?
Another common explanation for worm emergence is that rain sounds like predators, so the worms come to the surface to escape. Moles, common earthworm predators, make vibrations in the soil as they hunt.
A tradition in the Appalachians and elsewhere, called worm grunting or fiddling, involves using a saw or stick to make vibrations on the soil’s surface. This brings worms to the top that are then harvested for bait. Essentially, humans are mimicking the sounds of hunting moles. (I admit I have tried this without much luck).
The predation-escape theory suggests that the patter of raindrops is also similar to the sound of moles. University of Wisconsin professor Thea Whitman notes that this theory has never been demonstrated in laboratory tests. It always seemed like an unconvincing explanation to me. After all, worms emerge after a prolonged, misty rain that doesn’t strike the ground with as much force as they can