Friday May 25, 2018




All segmented worms belong to the Class Oligochaeta in the Phylum Annelida.


In the bushveld the main segmented worms, or annelids, are the earthworms. If you look closely at an earthworm one would think that they are anatomically pretty simple and probably even less sophisticated than snails and slugs (molluscs). However their anatomy indicates that in evolutionary terms annelids are more complex than the molluscs. 


The main characteristics of the annelids are:

·         They have no skeleton.

·         They are ectothermic.

·         All annelids are hermaphrodites. They have both male and female organs but still have to mate (sperm is transferred reciprocally) in order to produce viable young. There are exceptions some are parthenogenetic but generally they cannot fertilise their own eggs.

·         They are live bearing.

·         Annelids are covered with a very thin cellophane like cuticle which cuts down on moisture loss from the body.

·         Most can survive for several weeks under water providing there is oxygen in it.

·         Annelids are segmented, with each segment bearing the same fundamental structure as all the other segments, although minor differences can occur between some segments. By distributing organs along many segments it is less life threating to the annelid should one segment (organ) be damaged.

·         Young annelids usually just add new segments as they mature by simply making new copies of the body’s last segment.

·         They have the ability to replace or replicate certain lost or damaged segments. The extent varies between species, depends on the extent of the damage.

·         Scientific findings show that the following is possible, two individual worms can be obtained from one bisected worm; the head is capable of regrowth should it be removed in some species.



Benefits of earthworms:


·         Biological:

The earthworm is essential in the process of converting dead organic matter into a rich humus, which is essential for plant growth. This is achieved by the earthworm shredding and partially digesting the organic matter together with earth which is then secreted.


·         Chemical

The secretions in the form of casts consist of nitrogen, phosphates and potash. Where there is large quantities of organic matter the weight of the casts produced may be more than 4.5 Kg per year. Another good reason for not sweeping your stand back to bear earth.


·         Physical

Due to the burrowing action of the earthworm, it is of great importance in keeping the soil structure open which allows for the processes of aeration and drainage to occur.

Threats to earthworms:


The application of chemical fertiliser, insecticides and herbicides can have a disastrous effect on earthworm populations (as well as all other insect life). Even if not actually killed they can accumulate these pollutants (lead, cadmium, mercury etc) and dioxins at levels of up to twenty times higher than that found in the soil, which in turn are passed on at lethal dosages to the wildlife which feed upon them such as mongoose, moles, birds, frogs etc.


Therefore the most reliable way to maintain or increase the levels of worm population in the soil is to avoid the application of artificial chemicals, as well as allowing the natural organic matter to remain. Do not continually keep clearing the leaves away. It serves absolutely no purpose from an environmental aspect and is in fact detrimental to the bushveld.


50/50 TV program:

One of episodes discussed “Giant earthworms” which was very interesting. These Giant earthworms (Microchaetus skeadi) are found mainly in the Nama karoo biome of South Africa, and a similar species is also found in Australia as well.

The general size of these earthworms is about 2 meters with 3 meters not being that uncommon. Over the years there have been a few which have measured over 5 meters with the largest recorded being 6.6 meters long which was found near King Williams Town in 1967. Perhaps this record has been broken but if it has I am not aware of it.

In Australia the Giant earthworms there are somewhat smaller, averaging between 1 and 2 metres in length. They are now legally protected as they were concerned that there numbers may be diminishing due to pesticides, herbicides and various other chemicals.

In South Africa no one seems too concerned about whether or not our Giant earthworms are also vanishing and at present they are not protected in any way.


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