While Charles Darwin is best known for the Origin of Species, which detailed his evolutionary theory and became one of the most influential and controversial books in history, it is by no means his most important work.

Not according to him, anyway. He believed his most vital contribution was his research into... earthworms. The humble earthworm, he reckoned, is one of the most important species on the planet. Such was his fascination with these multi-segmented creatures that he published, on October 10, 1881, a work with the rather snappy title of The Formation of Vegetable Mould Through the Action of Worms.

The title becomes a bit more interesting when 19th-century science is applied to the term “vegetable mould” - the translation is close to “top soil”. Therefore, Darwin claims in The Formation of Vegetable Mould Through the Action of Worms, that said worms are responsible for making soil.

How do they achieve this? They consume decaying food and plant debris, their bodies process the matter into nutrients, then they release the nutrients into the soil via their castings - otherwise known as poo. In short, they drastically influence the properties of soils for the better.

They’re obviously important creatures - but so important that one of the world’s most influential minds would devote many a year to researching them? Consider this: earthworms could reduce the need for chemical fertilisers and pest controllers by making nutrients more readily available, controlling rain runoff, and suppressing pests and diseases. Researching and understanding these creatures and how they could be used in agriculture would be of massive value to farmers and, ultimately, consumers.

Furthermore, one of the most fun aspects of earthworms is that if you cut them in half, they’re likely to survive. This is, of course, not advocating that teachers and students alike hack away at their resident earthworm population but instead serves to reassure readers that an accidental massacre with a spade in the garden is no reason for a minute’s silence.

They are incredibly resilient. The segments of the earthworm, visible externally as rings, are separated by internal partitions. If they’re not too badly damaged - that is, if about half the body survives the blow - they may regenerate their posterior portion. They do not, contrary to popular belief, become two worms.

Some wonderful worm facts: Darwin estimated that if an acre of good soil contained 63,000 earthworms, they would deposit two inches of new top soil every 10 years; a square metre of cropland can contain 30 to 300 earthworms; there are 2,200 earthworm species, found all over the world except in arid and arctic regions and ranging in size from 2.5cm to three-metre giants in the tropics; all earthworms have male and female reproductive systems; earthworms are a major cause of the burying of ancient cities and monuments; most earthworms make their tunnels at least a metre deep; the circulatory system of an earthworm consists of five hearts - these pump blood from the upper vessel to the lower vessels, which in turn carry and distribute the blood to the different segments of the worm.

Perhaps the most incredible fact is that the nervous system of an earthworm is comparable with the human nervous system. It is sufficiently complex to store memory. In 1929, a scientist found that an earthworm in a Y-shaped tube would learn to avoid one branch of the tube if an electrode that gave electric shocks were placed in it. This quite fascinating creature led Darwin to write a glowing accolade in The Formation of Vegetable Mould Through the Action of Worms:

“Few animals have played such a significant role in the history of the world as these lowly organised creatures.”

Hear, hear.

Worm Digest www.wormdigest.orgCharles Darwin and Darwinianawww.sc.edulibraryspcollnathistdarwindarwinindex.htmlThe Voyage of the Beaglewww.literature.orgauthorsdarwin-charlesthe-voyage-of-the-beagle