How Does an Earthworm Move?
Earthworms are essential to any garden. They help to aerate and create better drainage for the soil, and leave behind added nutrients through their organic waste matter. They are incredible little creatures that live and move largely beneath our notice, but provide such a service to the environment that they deserve to be examined more closely. Does this Spark an idea?
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Peristaltic Movement
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The movement of an earthworm can be compared to food being processed through a human's intestinal tract. Circular and longitudinal muscles work together to push and retract, squeezing food along our digestive tract. An earthworm uses the same type of peristalsis for locomotion.
Long and Narrow to Short and Fat
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If you've ever watched an earthworm, you probably remember seeing them bunch up, then elongate, repeating the process as they move along the ground. This contraction and relaxation of the circular rings or segments along their body is what helps them scoot across the ground.
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Bristles
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The presence of tiny bristles called "setae" on the underside of an earthworm also help in the bunching and relaxing movements it makes. These bristles grip the soil like little hooks, giving the earthworm an added boost as it creeps along.
Castings
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As earthworms move through the soil, they consume the soil ahead of them, process it in their bodies, and then expel the waste from the other end. These deposits of excreted material are called "castings" and are visible on the surface of the soil. Some homeowners want perfect, manicured lawns, sans earthworm castings, but the presence of these long coils of waste matter actually indicates beneficial earthworm activity.
Tunneling
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Earthworms do not have skeletons and are basically moving lengths of muscled segments. Their tunneling underground creates channels that allow water and nutrients to penetrate more easily through the soil.
When Not to Move
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It's fun to watch a robin try to tug an earthworm from the ground. The reason the job isn't always as easy as it seems for the robin is because an earthworm inside its burrow can latch onto the soil using the tiny bristles under it, and then bunch up, fattening the lower half of its body into a plug at the burrow opening.
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References
Resources
- Photo Credit Earthworms (publicdomainpictures.net)
