Aussi earthworm - Didymogaster sylvaticus

Every fortnight at Marlene's place, for a couple of years now, I have been sharing some special time with a very unusual group of individuals.

But you know how it is - you get talking, you get involved, time passes, and before you know it, you realise that you haven't introduced yourselves properly - in fact, you don't even know each others names!

Well, next time I visit Marlene's I can formally apologise for this neglect, and say G'day properly. Thanks to the kind and helpful people at the Australian Museum, I now know that I have been hanging out with Didymogaster sylvaticus, a most unusual earthworm.

Just going back a little bit, I owe a debt of gratitude to Marlene for getting us (me and the earthworm that is) together. Marlene is a wonderful, generous and tenacious lady whom I am very glad to have met as a result of my gardening activities. She brought me in to clear a small part of her garden which was completely over-run by well established layers of Jasmine (Jasminium polyanthum) and Trad (Tradescantia fluminensis). That job is a story in itself, to be told another time (for more information on these and other weeds in our area go here), but the important thing is that in the process of that clearing I made my discovery. There, under the thick and damp layers of Trad I started to come across these earthworms that I had never seen before.

The first distinguishing feature is their size - or rather their thickness, which is about that of an adult finger - about 1.5cm. When fully elongated they seem to stretch up to about 15cm or more. Another feature is their colour which can vary from deep red to purple. They are very slow moving and when disturbed do a couple of things. Firstly they contract down to about half their normal length and remain motionless. If the disturbance actually involved a contact with their skin, they contract so quickly that they emit several fine jets of liquid that rise easily up to 20cm in the air, and in the direction of the disturbance. For most of the period of my aquaintance with them, they have been fairly regular in size. However, for the first time, and when I took these photographs in April, I noticed several small ones and they all had a rather purple tinge to them..

Kelly from the Australian Museum was able to add the following information.

“They are Didymogaster sylvaticus, commonly known as ‘frankfurter’ or ‘squirter’ earthworms because of ther size appearance and behaviour. These worms range from bright red to deep purple in colour and usually grow to a length of 15 - 25cm - although some have been recorded up to 46cm in length. These worms are relatively common throughout coastal New South Wales, displaying some unusual behaviour when scared or disturbed - hence their ‘squirter’ earthworm name. Their body will contract, and as the pressure increases from this motion, fluid is emitted at a very fast rate from pores along their back.”

She was also able to direct me towards the following information link at Channel 9 programme Burke’s Backyard

The worm was first described scientifically and named in 1886 by J.J Fletcher. This date sits between the publication of Charles Darwins book on earthworms five years earlier, and Henry Parkes famous 'Tenterfield Oration' in 1889. Parkes' estate in the Blue Mountains includes what is now Marlene's garden, and it is tempting to think that he once walked over the ancestors of these photographed individuals as he pondered the future Federation and Constitution of Australia. Aboriginal people have, of course, lived in this area for at least 25,000 years and probably knew it as well, but by another name, perhaps lost now.

The Australian Faunal Directory advises that D.sylvaticus occurs in the coastal fringe of NSW, and that it is relatively common. However, in five years of working in Blue Mountains gardens between Glenbrook and Mt Victoria, I have never seen it anywhere else. I have only found it on these narrow sandstone rock shelves in one area of the Mountains. Curiously, these rock shelves have accumulated some very rich soil around them - quite unlike the poor, thin sandy soil immediately above and below them, and which is the norm for most of the Blue Mountains. Did the dark coloured, crumb structured soil arise from the years of dense weed cover, or from runoff from above, or from the constant water seepage through the cracks of the sandstone? Is Didymogaster sylvaticus involved somehow, either by cause or effect, or is it all just a coincidence? By clearing the cover of noxious introduced weeds, am I robbing this local native of a beneficial environment?

If you knew Marlene, you would have guessed by now that 'the small corner' in fact turned out to be the entire weed infested garden. Maybe she thought she would frighten me off if I knew what her grand plans were too early. Her success in transforming her once neglected wasteland into a beautiful terraced native garden has already persuaded (by example) one neighbour to start down the same path, while another is thinking about it. In parallel with the garden transformation, she is also busy going through local records, researching the history of the area with a view to having its similarly neglected national significance recognised.

How is it that, in different ways, both Marlene and her uncommon garden occupant are thriving on neglect? Next time we meet, and after the appropriate and belated introductions, I will delicately attempt to bring this questions into my conversation with the enigmatic earthworm.

I'll let you know how we get on.