Earthworms’ Role In The Ecosystem

Charles Darwin is well known for his work on natural selection. He published widely on topics ranging from barnacles to geology to plants. He travelled the world and saw many unusual animals. Near the end of his life in 1881, he wrote in The Formation of Vegetable Mould,

It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.

Darwin, of course, was referring to earthworms.

Earthworms may lack the charm or excitement of more familiar animals, but their contribution to our world is significant. These ‘lowly creatures’ play a vital part within the natural soil ecosystem. They are also valued for their contribution to ecosystem services – ecosystem functions that are of direct benefit to humans through their action on soil processes.

Earthworm benefits to ecosystems

Earthworms’ role in the ecosystem

Earthworms are sometimes known as ‘ecosystem engineers’ because they significantly modify the physical, chemical and biological properties of the soil profile. These modifications can influence the habitat and activities of other organisms within the soil ecosystem.

Earthworms influence (and benefit) the soil ecosystem in a number of ways:

  • Recycling organic material: Earthworms, along with bacteria and fungi, decompose organic material. Most people know about earthworms and compost, but earthworms do the same in pasture soils, decomposing dung and plant litter and processing 2–20 tonnes of organic matter per hectare each year, and recycling leaf litter under orchards and in other forested areas.
  • Increasing nutrient availability: This happens in two ways: by incorporating organic materials into the soil and by unlocking the nutrients held within dead organisms and plant matter . Nutrients like phosphorus and nitrogen become more readily available to plants after digestion by earthworms and being excreted in earthworm casts. Scientists have measured up to five fold increases in nitrogen availability in earthworm casts compared to undigested soil. Earthworms also take nutrients down through the soil profile, bringing them into closer contact with plant roots.
  • Improving soil structure: Earthworm burrows alter the physical structure of the soil. They open up small spaces, known as pores, within the soil. When earthworms are introduced to soils devoid of them, their burrowing can lead to increases in water infiltration rates of up to 10 times the original amount. This brings water and soluble nutrients down to plant roots. Burrowing also improves soil aeration (important for both plants and other organisms living in the soil) and enhances plant root penetration.
  • Providing food for predators: Earthworms, like all creatures, are part of food webs. Birds are well known predators, but native earthworms are also food for endangered and endemic land snails.

Earthworm benefits to humans

New Zealand scientists have had a unique opportunity as far as earthworm research is concerned. Once land was cleared for production agriculture, native earthworms quickly disappeared. Unless non-native species of the lumbricid family were introduced to the area, earthworms were absent for periods of time. Scientists have been able to investigate the effects of introducing earthworms to pastoral lands and quantify the benefits they provide.

Earthworms provide these ecosystem services to humans:

Earthworms’ role in the ecosystem

  • Increasing pastoral productivity: Once lumbricid earthworms become established, pastoral productivity increases by 25–30%. This is equivalent to 2.5 stock units per hectare. Earthworms remove the surface thatch material that can block water from entering the soil, as the thatch can cause it (and soluble nutrients) to run off.
  • Facilitating and accelerating mine restoration: By increasing soil fertility, recycling waste products and providing food resources for predators, earthworms help to restore functioning ecosystems both above and below the ground.

Trish Fraser, a soil scientist and earthworm expert says, “The next time you see an earthworm struggling on the footpath, perhaps you will be kind to our little underground ally. Indeed, perhaps you will also think about the rest of the large army of earthworms working hard for us below the ground. Maybe then the important role that this underground army plays in our lives will be forgotten no more.”

Nature of science

Humans are part of the Earth’s ecosystems. Our activities, such as clearing native forests for agriculture or introducing lumbricid earthworms, alter the balance in ecosystems.

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The giant, native Powelliphanta snails are carnivorous and eat earthworms that they slurp like spaghetti! View a video of their life cycle on Te Ara – The Encyclopaedia of New Zealand.

Common Earthworm

The reddish-gray-colored common earthworm, often called a night crawler in the United States, is familiar to anyone with a fishing rod or a garden. They are indigenous to Europe, but are now abundant in North America and western Asia.

Earthworm Segements and Burrowing

Earthworms’ role in the ecosystem

Typically only a few inches in length, some members of this species have been known to grow to a serpentine 14 inches. Earthworms’ bodies are made up of ring-like segments called annuli. These segments are covered in setae, or small bristles, which the worm uses to move and burrow.

Night crawlers are so named because they are usually seen feeding above ground at night. They burrow during the day—typically keeping close to the surface—capable of digging down as deep as 6.5 feet.

The worm’s first segment contains its mouth. As they burrow, they consume soil, extracting nutrients from decomposing organic matter like leaves and roots. Earthworms are vital to soil health because they transport nutrients and minerals from below to the surface via their waste, and their tunnels aerate the ground. An earthworm can eat up to one third its body weight in a day.

Earthworms’ role in the ecosystem

Night crawlers also mate on the surface. They are hermaphroditic but do not self-fertilize. Following mating, each worm forms a tiny, lemon-shaped cocoon out of a liquid secreted from its clitellum, the familiar-looking bulge seen near the first third of the earthworm’s body. The sperm and egg cells are deposited inside the cocoon, and it is buried. After a two- to four-week gestation period, the baby worms emerge.

Impact on the Ecosystem

Earthworms are a source of food for numerous animals, like birds, rats, and toads, and are frequently used in residential composting and as bait in commercial and recreational fishing. Their numbers are strong throughout their range—they’re even considered agricultural pests in some areas—and they have no special status.

Named «Dave» by its discoverers, it is 15.75 inches long and weighs as much as a small chocolate bar. Its size is unusual because earthworms have many predators and normally do not survive in the wild to reach Dave’s size.

Earthworm: a description of lifestyle and characteristics, benefits to the soil and role in nature

Earthworms are intriguing creatures that play a discreet, yet vital role in the natural cycle of life. In this BiologyWise article, we present to you important information about the biological classification (taxonomy) and characteristics of the common earthworm.

I doubt whether there are many other animals which have played so important a part in the history of the world, as have these lowly organized creatures. ―Charles Darwin on the importance of earthworms.

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The earthworm plays a major role in the proper functioning of the ecosystem of the soil. It acts as a scavenger, and helps in the recycling of the dead and decayed plant matter by feeding on it. It increases the soil fertility and is often referred to as a farmer’s friend. It burrows the soil and ingests soil particles coming in its way. Both these processes aerate the soil and help in the inter-mixing of the soil particles of the upper and underlying layers.

Earthworms are found all over the world in any type of soil, except the waterlogged and sandy areas. Let’s discuss in brief about the taxonomic classification and characteristics of earthworms.

Taxonomy of the Common Earthworms

Though all species of earthworm are classified in the same class and order, they do not belong to the same family. Following is the classification of the common earthworm (Lumbricus terrestris).

Kingdom: Animalia

Earthworms are eukaryotic (cells have nuclei), multicellular organisms. They have the ability to move and depend on dead plant materials and microorganisms for food.

Phylum: Annelida

Earthworms’ role in the ecosystem

Earthworms belong to the phylum annelida which comprises segmented worms. The segments of the earthworm’s body, known as annuli, are separated by transverse dividing walls known a septa. They have multiple segments, with those belonging to a species possess organs in same segments. In some species of annelids, septa are less defined or even absent.

Class: Clitellata

Earthworms have clitellum, a type of collar that secretes clitella or cocoon during reproduction. The head of earthworm is less developed than other annelid species.

Subclass: Oligochaeta

Earthworms have setae or bristles on the body, which helps them to attach to the surface during movement. They lack lateral appendages or parapodia, which is a characteristic feature of the subclass polychaeta.

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Order: Haplotaxida

The common earthworm is categorized under Haplotaxida, which is one of the two orders of Oligochaeta.

Family: Lumbricidae

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The common earthworm belongs to Lumbricidae which is one of the largest earthworm family. About 33 species of earthworms are identified under this family.

Characteristics of the Common Earthworm

The common earthworm (Lumbricus terrestris) resembles a cylindrical tube, with an average length of about 7 cm. – 8 cm., with some members of this species even growing to 35 cm. They are found abundantly in North America, Europe and western Asia.

The reddish-gray colored body of the earthworm is segmented, and the vital organs are present in particular segments. The skin is covered by a moist mucous layer that serves the main purpose of respiration (exchange of air). An earthworm does not have any locomotory organs and therefore moves by means of muscle contraction and relaxation.

The earthworms are also known as night crawlers because they are usually come above ground during the night. During the day, they burrow the ground using their strong toothless yet muscular mouths. While burrowing, an earthworm feeds on dead plant materials and organic matter present in the soil. The ingested food is broken down into finer particles in its muscular stomach also known as gizzard. The fine food particles are acted upon by various enzymes for digestion process. Useful nutrients are absorbed and undigested soil and other particles are passed out as worm casts. Studies have revealed the presence of useful soil microorganisms in earthworm casts.

The earthworms also transfer nutrients and minerals from the earthen layers below, to the surface above through their waste. The small burrows that they create keeps the soil aerated. Thus the earthworms play a vital in maintaining the health of the soil.

Earthworms are hermaphrodite, meaning both male and female sex organs are present in the same body. However, reproduction takes place via cross-fertilization. The eggs are enclosed in an egg casing or a cocoon. The juvenile earthworm resembles an adult worm, except that it lacks sex organs. It attains sexual maturity within 2 – 3 months after hatching.

One of the characteristic features of many different species of earthworms is their ability to regenerate lost segments of their bodies. The lifespan of the earthworm varies depending upon the species; the common earthworm can live up to 6 years in the wild. Common predators of the earthworm include birds and other small mammals.

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Earthworm adaptations

Adaptation is an evolutionary process whereby an organism becomes increasingly well suited to living in a particular habitat. Natural selection results in helpful traits becoming more common in a population. This occurs because individuals with these traits are better adapted to the environment and therefore more likely to survive and breed. The timeframes for different types of adaptation are variable – behavioural adaptation can be a very quick process whereas structural changes may occur over a very long period of time.

Adaptation is also a common term to describe these helpful or adaptive traits. In other words, an adaptation is a feature of an organism that enables it to live in a particular habitat.

Most species of earthworms share some common traits or adaptations, such as their streamlined body shape. However, different species of earthworms have adapted to different habitats and occupy different niches within the ecosystem. As a result, earthworm adaptations are many and varied. In all animals, types of adaptations can be grouped into three main categories: structural, physiological and behavioural.

Structural Adaptations

Structural (or morphological) adaptations are the physical features of the organism. These include things you can see, like its shape or body covering, as well as its internal organisation.

These are some examples of structural adaptations of earthworms:

  • Each segment on an earthworm’s body has a number of bristly hairs, called setae (sometimes written as chaetae). These hairs provide some grip to help the earthworm move through the soil.
  • An earthworm has a streamlined body with no antennae or fins or arms or legs! This streamlined shape is an adaptation to living in narrow burrows underground and the need to move easily through the soil.
  • An earthworm has circular muscles that surround each body segment. It also has longitudinal muscles that run the length of its body. These two groups of muscles work together to help the earthworm move.
  • In order to get food into its mouth, an earthworm pushes its pharynx out of its mouth to grasp hold of its food. It then pulls the food back into its mouth and wets it with saliva
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Physiological Adaptations

Physiological adaptations relate to how the organism’s metabolism works. These adaptations enable the organism to regulate its bodily functions, such as breathing and temperature, and perform special functions like excreting chemicals as a defence mechanism.

These are some examples of physiological adaptations of earthworms:

  • Many earthworms secrete a mucus (coelomic fluid) that helps them to move more easily through the soil. In some burrowing species, this fluid forms a cement-like substance that lines their burrows to help keep the walls from collapsing. In the New Zealand native species Octochaetus multiporus, the mucus may also be part of its defence system as it is toxic to soil bacteria O. multiporus has another special adaptation – its mucus is bioluminescent! When it is disturbed, the O. multiporus earthworm squirts mucus from its mouth, anus and dorsal (underside) pores, and the fluid emits a bright orange-yellow light that glows in the dark.

  • When the environmental conditions in an earthworm’s habitat change, for example, the soil becomes too hot or too dry, many earthworms become inactive in a process called aestivation. They move deeper into the soil, coil into a tight ball, excrete a protective mucus and lower their metabolic rate in order to reduce water loss. They will remain like this until conditions become favourable again.

Behavioural adaptations

Behavioural adaptations are learned or inherited behaviours that help organisms to survive.

These are some examples of behavioural adaptations of earthworms:

  • Earthworms cannot see or hear but they are sensitive to vibrations. Birds looking for food or humans collecting earthworms for bait stamp on or vibrate the ground in some manner, causing earthworms to move to the surface. Perhaps this is to escape from moles, whose primary food is earthworms. We don’t have moles in New Zealand, but some people think that earthworms carry a ‘memory’ of this predator and still respond by leaving the ground.
  • Earthworms are sensitive to light. Most species spend their days in their burrows or in the soil or leaf litter. In general, you usually find them on the surface at night.
  • Earthworms lose moisture through their skin. They move out of their burrows to migrate or reproduce when the ground is wet with dew – one reason why we may see them in the early morning.

Activity idea

Think you can work as a worm wrangler or ‘grunter’? Try this activity to bring some earthworms to the ground’s surface.
Catching worms using ground sounds

Earthworm: a description of lifestyle and characteristics, benefits to the soil and role in nature

Korea has developed a unique food culture connected to its long agricultural history. Recently, interest in Korean food, especially regarding its health benefits, has greatly increased. However, there are insufficient resources and research available on the characteristics and definitions of Korean cuisine.


Researchers and professors of the food and nutritional sciences in Korea began working together in April 2015 in order to establish cohesive definitions and concepts to be used in dialogue related to the Korean diet (K-diet). The 100 most representative Korean dishes (K-food) were selected by evaluating their role in tradition, culture, and health promotion.


Although the K-diet has been widely discussed in regard to raw ingredients, traditional cooking methods and technology, fundamental principles, and knowledge, it would be valuable to preserve the traditional methods and knowledge of Korean foods rather than focus on the raw materials themselves. Korean meals have historically been served with bap (cooked rice), kuk (dishes with broth), kimchi, and banchan (side dishes) to be consumed at the same time. As traditionally baking or frying were not common cooking methods, Koreans tended to use fermenting, boiling, blanching, seasoning, and pickling. Among these methods, the most characteristic method is fermentation. The process of fermentation enriches food flavors and preserves foods.


The K-diet is composed of bab (cooked-rice) and kuk, and various banchan with one serving called bapsang. Kimchi is always served at every meal. The principal aspects of the K-diet include proportionally high consumption of vegetables, moderate to high consumption of legumes and fish, and low consumption of red meat. Banchan is mostly seasoned with various jang (fermented soy products), medicinal herbs, and sesame or perilla oil.

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