More about earthworms
The famous scientist Charles Darwin (1809-1882), best known for his work on evolution, spent over 40 years studying earthworms and wrote a book on them.
People found his interest in the simple earthworm funny – as you can see from this cartoon published in the satirical magazine Punch in 1881.
Earthworms are the world's unsung heroes. They loosen and mix up the soil, break down and recycle decaying plant matter and fertilise the soil by bringing nutrients closer to the surface. They are of vital importance for our farming and gardening. Charles Darwin referred to earthworms as ‘nature’s ploughs’ because of this mixing of soil and organic matter.
The term Earthworm refers to a specific group of invertebrates rather than a single species.
Earthworm biology:
An earthworm consists of a digestive tube housed within a thick cylindrical muscular tube that forms the body. The body is divided into segments.
All segments, except the first, have eight retractable bristles which help the earthworm to grip surfaces as it moves.
Earthworms breathe through their skin, so burrowing worms have to come to the surface when it rains or risk drowning.
Worms do not have eyes and prefer the dark. They can sense light and dark and prefer dark conditions because they are easily damaged by the sun’s UV rays and will dry out quicky.
Earthworms are both male and female in one body, though it still takes two worms to reproduce!
If you accidentally cut a worm in two, only the head end will regenerate and survive but only if the damage isn’t too extreme.
You can find more about the life cycle of earthworms from the Earthworm Society website.
The importance of earthworms for soil condition:
Worms eat soil and organic matter such as fallen leaves, mixing these ingredients together and then excreting them.
Worms can move an amazing amount of soil for their small size. A worm can eat its own weight in soil in one day.
Worm casts which are seen on the surface of lawns are made by 5 species of worms, called casting worms. Mostly found from autumn to spring, these casts are by-products of eating (ie worm poo!).
Earthworms burrowing through the soil create channels that add oxygen to the soil and allow carbon dioxide to escape. The channels also allow rain to drain away.
There are 31 different species of worms in the UK which can be divided into four categories:
| Type | Description | Actions | Feeds on |
|---|---|---|---|
| Anecic earthworms | Big, darkly coloured at the head end (red or brown) and have paler tails | Create deep vertical permanent burrows | Feed on leaves on the soil surface that they drag into their burrows. Casting worms. |
| Endogeic earthworms | Pale colours, grey, pale pink, green or blue | Burrows horizontally in upper soil layer as it moves and feeds | Feeds on soil |
| Epigeic earthworms | Small, bright red or reddy-brown, but not stripy | Live on the surface of the soil in leaf litter, rarely burrow | Feed on the leaf litter |
| Compost earthworms | Small, bright red in colour and stripy | Live above ground in compost, or areas very rich in rotting vegetation | Feed on rotting plant material and dung |
You can find even more about earthworms from the Earthworm Society website.
Worms form an important component of the diet of many animals large and small, including birds like the blackbird and gulls, and mammals like the mole, hedgehog and badger. Perhaps the surprise is the importance of the tiny earthworm to the diet of a large mammal like the badger - over 80% of the badger diet consists of earthworms.