Worm divides opinion

It’s the time of year when many gardeners are cleaning out their plots and digging them over. 

Digging inevitably exposes earthworms and sometimes the worms get damaged in the process. There is an old belief that if a worm gets cut in half by a spade it turns into two living worms. This belief was always ridiculed by biologists, at least until relatively recently when some impeccable scientific research proved that it does occasionally happen.

Twenty seven species of earthworm have been recorded in Ireland and it seems that each species has a different reaction to being cut in two. A worm’s body consists of a number of segments — the precise number depends on age and species but typically there are 20 to 50 of them. Most earthworm species appear to be able to survive having some of their rear segments removed. The rear end dies but the front end eventually regrows the missing segments, though sometimes the re-grown segments differ from the rest of the worm in either colour or diameter.

Some scientists have devoted years to cutting up worms of different species and observing how many segments they are capable of regenerating. It sounds like a rather gruesome field of research to me, but I suppose the advancement of science demands such things.

In the 1970s one of these scientists, a man called Gates, published a paper stating that in certain rare circumstances both parts of a bisected worm could regenerate, proving that the old folk belief was true and that a worm cut in half could turn into two worms. His paper was not widely read and many biologists are unaware of its findings.

But despite this discovery the fact is that worms are immensely valuable items in your garden and that cutting them up while you’re digging does them no good. For this reason, whenever possible, I use a garden fork rather than a spade because it reduces the damage.

Worms are valuable in several ways. They spend most of their lives eating their way through the soil. They take in organic matter at their front end, break it down in their digestive tract, and expel it from their rear end in the form of a rich organic fertiliser. One large worm can produce four or five kilos of this fertiliser in a year.

In addition, each worm acts like a piston pumping air through the soil and also helping with drainage as it travels through its tunnel. They also vary the depth at which they work according to soil moisture and temperature.

As they go up and down they mix sub-soil and top-soil, which is one of the main things we are trying to do when we dig the garden. They lubricate their underground travels by producing slime which is sticky and helps soil aggregation, as well as being rich in nitrogen. So you really do need to look after them.

 

Nature Table

WOODLOUSE - (Oniscus asellus)

[timg]Woodlouse_large.jpg[timg]

Woodlice are familiar creatures in gardens, and sometimes in houses. They have several local names and are often called slaters in Ireland. 32 species have been recorded in this country, some of which live in water but most on land.

One Irish species, usually called the pill bug, has the ability to roll itself up in a ball if it’s threatened. They are crustaceans, not insects, with 7 pairs of jointed legs, and are related to marine crabs and shrimps.

Woodlice are largely harmless and mostly eat dead and decaying vegetation, recycling their nutrients. Occasionally they eat living vegetable matter, usually young seedlings. They tend to be nocturnal, hiding in crevices or under rocks, logs or plant pots during the day.

They are an important source of food for birds, small mammals and some spider species, which specialise in hunting them.


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