Back to Contentshttp://www.nectar.com.au/~stylesie/worms.html -- Lawrence F. London, Jr. mailto:london@sunSITE.unc.edu http://sunSITE.unc.edu/InterGarden mailto:llondon@nuteknet.comTitle: Australian Earthworms
This page is an on-going project and will be updated and improved as I find the time. Any comments and critiques about content are most welcome. Email Colin Styles .
Australia has one of the most ancient and poor soil structures of any country on earth. Australia's earthworm population is small when compared to places like Europe. Our worms are generally poor soil builders and unused to improved pastures and composting situations. Many European and Asian worms have been accidently introduced to Australian soil over the centuries and it is these varieties that you will find in farmland and compost heaps the native types generally sticking to unimproved land.
Of the 3000 or so earthworm species identified worldwide, about 300 are native to Australia
Soil Earthworms will have biota (associated life forms) six times that of the worms. Good soil, with a density of five thousand worms per meter, can have 5 tonnes of worms per hectare and thirty tonnes of associated biota, all under the soils surface. This amount of life will aerate and fertilise more than 900 tonnes of soil per hectare each year.
In Europe Earthworms can build up the surface layer of topsoil at a rate of two milimeters per year. In Australia the rate is closer to half a milimeter per year.
Worms help to break down water resistant root mats that form underneath the surface and open up channels to aerate the soil and make it more water penetrable. Worm populated soil bacomes wet faster and deeper and holds the moisture longer. The worm burrows are coated in a nitrate rich mucous which helps to shore them against damage and provides plants with an easily digestible nitrate supply.
Nitrogen and carbon are separated in the worms gut and the nitrogen is deposited in the worms casting in a plant soluble form.
Worms are Hermaphrodites, they have both male and female sexual organs. One worm has two pairs of testes and two ovaries. Mating worms move together head to head and overlap thier bodies until they are nose to clitellum. A thick layer of mucous is excreted which wraps the worms tightly together. Sperm is ejected by both worms and collected and stored by the worms partner in special ducts. After the worms separate the clitellum quickly exudes an albuminous ring. The worm begins to wriggle out of this ring which slide forward over the worms head. On its way it passes over the ovary ducts of the worm and then the sperm storage ducts. After the worm finally wriggles out of the ring it closes and forms a capsule containing fertilised eggs. A capsule contains between 1 and 20 baby worms but usually averages out at 4 per capsule. Not all of the sperm is used each time a capsule is formed, so each worm might produce several capsules from one mating.
Worms do not mate between species, there are no worm hybrids. This is because besides any genetic incompatibilities the sex organs of different species do not correspond. Worms need to be of equivalent size and the same species in order to produce offspring.
Worms are extremely well muscled, they have longitudinal muscles and encircling muscles which cause the worm to stretch and contract its body in a co-ordinated fashion. When the worm is fully extended the worm will anchor its anterior (front) end to the soil and pull its posterior (rear) end up. The worm can also do this in reverse in a very graceful fashion. The worm anchors itself to the soil by using retractable spines calles Setae. These Setae are in pairs on each worm segment.
Manure worms can be used for composting and are generally NOT very good in the garden (they need nutrient rich bedding, manure or food scraps). They are the ones that you can buy in bait shops and worm farms. Two types, Reds (Lumbricus rubellus) and Blues (Perionix excavatus) can survive and even thrive in well mulched soil but never introduce adult Reds or Blues to the garden, they will die. Introduce worm capsules (eggs) to the soil and the young worms will adapt more readily to the new environment. Commercial worms have a very high breeding rate and eat thier own weight in bedding and food per day. They will eat anything that was once alive but not while it is alive so are perfect for home and indoor composting.
These worms do more for soil building. They burrow in relatively nutrient poor soil and clay, mix it with mulch and excrete it onto the surface as castings. Their burrows aerate the soil and make it more water retentive, microbe rich and because they are lined with mucous bind plant usable nitrogen to the soil. They are much harder (read expensive) to cultivate commercially than composting worms.
The best way to attract worms into your garden is to mulch it. Create plenty of worm food and worms will flock to you. This does take time though especially if you only have Australian native earthworms in your garden, they breed slowly and are poor performers compared to the European imported worms.
Next time you mow the lawn, leave the catcher behind and leave the grass clippings on the lawn. Within 12 month you could have worm densities of 5000 per square meter (under ideal conditions). At this density they can build your soil up by cm per year. Worms prefer a soil PH on the acidic side of neutral, but not too acidic. As they work they reduce soil acidity via a Calciferous gland, this combined with a light dusting of garden lime (or crushed egg shells) is great for soil PH.
Worms are probably the best thing you can do for your garden, they've been building and fixing the soil for 600 million years long before we came along and started introducing chemicals.
A useful earthworm classification method is based on feeding behaviour and habitat. All worms fall into these categories somewhere. Generally, the nearer the base of the triangle the more useful the worm for soil building and the nearer the peak are manure (Commercial) worms.
Epigeic
/\
/ <--------------- Eisenia fetida (Tiger or Red Tiger)
/ \
/ <---------------- Perionyx excavatus (Blue or Indian Blue)
/ \
/ <------------ Lumbricus rubellus (Red or Blood worm)
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ \
/ <---- Lumbricus terrestris
/ \
Endogeic ---------------------------------- Anecic
Epigeic: Surface dwelling worms that ingest freshly decaying plant or animal residues.
Endogeic: Soil dwelling worms that ingest soil and extract nutrition from degraded organic matter.
Anecic: Burrow deep into the soil but forage at night on the surface for freshly decaying plant or animal residues.
Comments: Very active wigglers when exposed to sunlight. Worms exude amino acids that are lacking in fish which makes them almost irresistible to fishes and great bait. Prolific breeders
Comments: Very active wigglers when exposed to sunlight. Worms exude coelemic fluid which smells unpleasant and are therefore not suitable for fishing bait.
Comments: Very active wigglers when exposed to sunlight. Worms exude coelemic fluid which smells unpleasant and are therefore not suitable for fishing bait.
Comments: Very active wigglers, they also fluoresce when exposed to sunlight. They make good fishing bait and fetch a better price than Lumbricus rubellus. Thier breeding habits are prolific.
Comments: Externally identical to Perionyx excavatus with which they are often confused. Very active wigglers, they also fluoresce when exposed to sunlight. They make good fishing bait and fetch a better price than Lumbricus rubellus. Thier breeding habits are prolific and this Australian native worm is Parthenogenetic, ie self fertilising.
Comments: More information when I get it.
Earthworms in Australia
- David Murphy
- ISBN: 1 875657 09 6
Worms Downunder Downunder
- Allan Windust