All About Earthworms - Earthworm Facts & Information

About Earthworms

Commonly found in moist, compost and rich soils, Earthworms, although small, are actually one of nature's most important detrivores, and populations of Earthworms are often used as indications of soil health and environmental quality as they are sensitive to soil conditions and pollutants.

Belonging to the phylum Annelida, there are thousands of species of pale coloured common Earthworms, with the most common types belonging to the families Lumbricidae and Megascolecidae.

Earthworms body segments called annuli, are typically cylindrical and elongated and are covered in a mucous layer that helps them move through soil. They lack a skeleton and have a hydrostatic structure, relying on fluid pressure within their coelom (body cavity) for support.

Consuming soil and organic matter, the Earthworm's digestive system runs the length of their entire body, this includes their mouth and digestive tract. The nutrients are absorbed, and the rest is excreted as castings, which are rich in nutrients.

While native to different regions, some common Earthworm species have been spread globally through human activities, impacting local ecosystems. There also many different size Earthworms, for example, the largest species lives in Australia and is called the Giant Gippsland earthworm (Megascolides australis).

Worm Casts

Worm casts, also known as worm castings or vermicast, are nutrient rich waste of Earthworms and they play a role in enhancing soil health and fertility.

Worm casts are the digested soil and organic material that Earthworms excrete. As earthworms rapidly consume the soil and decomposing organic matter, they process these materials in their digestive system, breaking them down into finer particles and enriching them with nutrients. The species that leave worm casts usually live in permanent vertical burrows and draw plant debris and leaf litter down (known as anecic Earthworms)

Species of Earthworm UK

Endogeic Earthworms

Endogeic earthworms live within the soil and are often referred to as "soil dwellers." They create horizontal burrows and are usually pale in colour since they rarely come to the surface. These worms consume soil and organic matter within it, contributing to soil structure and nutrient cycling.

Epigeic Earthworms

Epigeic earthworms live in the leaf litter and the uppermost layer of the soil. They are typically small and have a bright red or reddish brown colouration. These worms do not create permanent burrows but move through the litter layer. They are crucial for the decomposition of organic matter.

Anecic Earthworms

Anecic Earthworms create permanent vertical burrows that can extend deep into the soil. They come to the surface to pull down organic matter into their burrows. These worms are typically larger and are important for soil aeration and nutrient incorporation from the surface to deeper soil layers.

What Do Earthworms Do

Playing several important roles in our ecosystem, particularly in healthy soil and fertility, there are some key things they do.

Burrowing to create tunnels as they move through the soil improve drainage and soil aeration, this allows water, and nutrients to move deeper into the ground.

Earthworms ingest soil and organic matter, this means they mix the soil layers and nutrients are distributed more evenly.

Compost Earthworms eat and live in decaying organic matter, such as decaying plant material and fallen leaves. Digested food is broken down into simplest compounds plants can easily absorb.

The waste excreted by earthworms, known as castings, is rich in nutrients like nitrogen, phosphorus, and potassium, making it an excellent natural fertiliser.

Burrows created by Earthworms make it much easier for plant roots to grow and access water and some Earthworm research suggests that Earthworms produce substances that can promote plant growth!

Earthworm Diet

The main part of an Earthworm's diet is soil. Decaying organic matter such as roots and leaves provide these animals with the nutrients they need because the soil particles and organic matter that earthworms consume is often coated with microorganisms like bacteria and fungi, which contribute to their nutritional intake.

When found in compost heaps, compost worms feed on partially decomposed organic matter, including fruit and vegetable scraps, coffee grounds, and other kitchen waste.

How Long Do Earthworms Live

In the wild, the lifespan of Earthworms can vary depending on species and environmental factors. Generally, earthworms can live anywhere from a few months to several years.

Common Earthworms, also known as 'night crawlers', can live up to 6-8 years in idea conditions. However, due to predators and environmental stresses, their lifespan is typically 2-3 years.

Compost worms, also known as red wigglers, typically have a lifespan of 1-5 years.

Earthworm longevity is influenced by several factors, including soil quality, moisture levels, temperature, and the presence of predators. Earthworms thrive in moist, nutrient-rich soil with moderate temperatures.

Adult Earthworm Breeding

All adult Earthworms are hermaphrodites, this means that each possesses both male and female reproductive organs. Despite this, they do require another Earthworm to breed.

Earthworm mating takes place on the soil surface during wet conditions to facilitate movement. Two Earthworms align and exchange sperm.

Once the breeding has taken place, the clitellum (the thick, glandular section of the body) secrets a mucus that forms a cocoon for the egg cells.

Containing the fertilised eggs, the cocoon is deposited in the soil. Depending on environmental conditions, it can take these eggs a few weeks, or several months, to hatch.

The cocoon, containing the fertiliased eggs, is deposited in the soil. Depending on environmental conditions such as temperature and moisture, the embryos develop and hatch as juvenile worms in a few weeks to several months.

The young worms emerge from the cocoon and gradually mature, which can take several weeks to a few months. They are smaller versions of adult earthworms and will grow and develop reproductive organs as they age.

Earthworm Predators

As an important part of the ecosystem, Earthworms have a variety of natural predators.

In the wild, many bird species, such as Robins and Starlings are known for feeding on Earthworms. They'll forage for worms on the surface of the soil, especially after it has rained as this is when the worms are more active on the surface.

Moles, Hedgehogs and Shrews all feed on Earthworms, digging through the soil to find these rich in protein worms.

Frogs, toads, and some species of lizards and snakes also eat earthworms. These predators often hunt for worms at night when they are more likely to encounter them on the soil surface.

While not typically thought of as natural predators, humans use earthworms as bait for fishing and sometimes for food in certain cultures.

Five Facts about Earthworms

1. Earthworms play a crucial role in soil health by aerating the soil as they burrow, which improves oxygen flow to plant roots. They also contribute to soil fertility by breaking down organic matter and excreting it as nutrient-rich castings.

2. Earthworms are hermaphrodites, meaning each individual has both male and female reproductive organs. During mating, two Earthworms exchange sperm to fertilise their eggs. After mating, each worm can produce a cocoon that contains the fertilised eggs, from which juvenile worms eventually hatch.

3. The lifespan of an earthworm can vary significantly depending on the species and environmental conditions. Some earthworms can live up to 6-8 years in ideal conditions. Additionally, Earthworms have the ability to regenerate lost segments, although the extent of this ability depends on the severity and location of the injury.

4. Earthworms are highly sensitive to light and vibrations. They lack eyes but have light-sensitive cells scattered throughout their skin, especially towards the anterior end. They tend to avoid light, which is why they are often found burrowing underground or emerging at night. Vibrations, such as those caused by predators or rain, can also trigger a response, causing earthworms to retreat deeper into the soil.

5. Earthworms are found all over the world, except in regions with extreme conditions such as deserts and polar ice caps. There are over 6,000 species of Earthworms, varying in size, habitat preference, and ecological role. The smallest species can be less than an inch long, while the largest, such as the Giant Gippsland earthworm in Australia, can grow up to 10 feet in length.