Epigeic species live at the soil surface and feed on plant residues and manure. Anecic species have the same food preferences, but live in a deep reaching permanent burrow system. Endogeic species seldom come to the soil surface and consume large amounts of soil from which they extract organic matter. Compost worms will seldom be observed in mineral soil, but can be abundant in manure and compost heaps. Commercially, these species are nowadays to produce vermicompost.
Approximately 22 earthworm species have been found in the Netherlands in the past, although only approximately 12 species are commonly occurring. Go directly to: Content Search box Breadcrumb. Twitter Whatsapp Linkedin Email. 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.
Earthworm Biology - The Science of the Natural Decomposers
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. If worms were dying due to moisture, or fleeing predators, you might expect to see a broad cross-section of a given worm population. After a rainstorm, not all of the worms of a given species come to the surface.
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When worms are brought to the surface with electricity, worm-grunting, or chemicals, many more worms are present. It is obvious that only a small percentage of the adult red worms are emerging during heavy rains. Think about this. You are not seeing young earthworms in your damp backyard. Many earthworm and soil experts have settled on a version of this explanation : Moving around the soil is relatively slow and difficult, even for earthworms.
They can cover a lot more ground on the surface. The problem is, earthworms need to stay moist. Most of the time, they would dehydrate if they were above ground. But when it rains, the surface is moist enough for worms to survive and remain hydrated. For a few species, they can more easily move about and find mates.
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For other earthworms, it may well just be a way to disperse and move into new territory. They can migrate much longer distances than they ever could underground. Of course, coming to the surface poses hazards. The earthworms are easy pickings for birds and other predators.
4. General Introduction to Earthworms, Their Classifications, and Biology
In our urban and suburban world, they also get trapped on sidewalks, patios and roads. The worms I encountered this morning gave the impression that their migration strategy was a failed one. But most worms survive. They move across the lawn or park and burrow back into the soil without any problems. There undoubtedly will be new research and new revelations about the lives and habits of earthworms.
The common creatures that live around us still hold surprises. Take a moment and observe the phenomenon happening in the natural world, right now, where we live. The surprises and wonders are right under our feet. Please note that all comments are moderated and may take some time to appear. This article is very timely.
What are Earthworms?
We had several days of rain in Santa Barbara. Most of these were already dried out. I was more surprised on two mornings to find worms that had crawled about three feet into our living room. They must have that entered the house by crawling under the door at night.
Needless to say, I was very curious about this migration of earthworms. Keep up the great work. I often move live earthworms off the sidewalk with my hand and drop them on nearby grass after rain. Good or bad idea? I move night crawlers that have crawled onto our crushed stone driveway onto grassy or dirt areas, too. Kindness is important to all living creatures.
Among my strongest memories of growing up in Denver pre-drought, is that of attending St. Vincent de Paul grade school. After the inevitable afternoon showers, the worms were up and about everywhere and the stinky boys would grab them and throw them at the girls.
I hated the smell of earthworms, too. Still do. So, no love lost here. Thanks for this thought-provoking post, Matt. Maybe it will pique the interest of a budding biologist who one day will discover the answer to this puzzle. I get to be Norm from Cheers and spread biophilia at the same time. Maybe the question should be posed: why do earthworms burrow?
Earthworm Biology - The Science of the Natural Decomposers
Perhaps their need for moisture leads them downward during dry spells following the water. I observed that after several months of flooding on the Skunk River in , some invasive species from Europe and Asia were exterminated. Native Diplocardia species were still there. I had collected all a few years prior. Thus some tolerated saturated soils and others did not. Soil atmosphere conditions are generally low in oxygen, so even brief periods of saturation can reduce oxygen availability rather quickly.
Oxygen has poor solubility in water. Earthworms surviving in water for weeks on end usually is with aerated water. Another thing: emergence with heavy rain is greatly reduced once plants have leafed out and are sucking water from the soil. Smell the water sheen, more likely. However, I do not recognize that bird — maybe some kind of European thrush. The photo in the articles describes an American robin Turdus migratorius , but the bird is more likely the European fieldfare, Turdus pilaris a thrush species in the same genus.