In Issue #36 :
The Remarkable Acellular Slime Moulds + The Kiwi Coast + Cave Diving + Almost a Flowering Plant
All the best,
In Issue #36 :
The Remarkable Acellular Slime Moulds + The Kiwi Coast + Cave Diving + Almost a Flowering Plant
All the best,
‘Slime mould’ is a not a term that elicits excitement in most people, nor does it conjure up images of great beauty. But slime moulds must be among the most remarkable of organisms! At one stage of their life they are single cell amoeba, whose definition is found in a Dictionary of Zoology, then they combine with others of their kind to form either a plasmodium – or pseudoplasmodium – defined in the Dictionary of Plant Sciences.
My fascination with slime moulds has been growing gradually since first reading about them in books about fungi. They were once placed in the same kingdom as fungi but are now in their own kingdom: the Protozoa.) Their sudden appearance is particularly intriguing. On one occasion I went outside to find three fruiting bodies in various colours of Fuligo septica on logs or stumps about 20-50 metres apart. This left me wondering about the stimulus for their sudden appearance.
In an attempt to find out more about slime moulds I purchased The Social Amoebae: the biology of cellular slime moulds, a small book written by John Tyler Bonner. Bonner (aka the ‘sultan of slime’) is professor emeritus of ecology and evolutionary biology at Princeton University who has worked and written about his ‘beloved slime molds’ for six decades. He writes in the preface that one reason for the book was to clarify in his own mind the complex nature of the subject of his life’s work. But rather than clarifying it for me, the information, initially at least, was bewildering. Then, after reading Virgil Hubregtse’s account of a talk given by Paul George (via the Australia Fungimap project, #28), I realised the reason for my confusion: there are three types of slime moulds!
The cellular slime moulds are mostly microscopic; the acellular slime moulds are the ones we see.
One of the most frequently encountered acellular slime mould is the aforementioned Fuligo septica. Its common names of either ‘dog vomit‘ or ‘scrambled egg’ slime mould evocatively describe its size and consistency. It appears on rotting logs, stumps or live vegetation during summer, first as a moist brightly coloured (usually yellow) blob, then, as the spores develop, it fades and gradually hardens. It is likely, given that many acellular slime moulds have a globally cosmopolitan distribution, that it was the one that featured in 9th century Chinese writings called ‘Kwei hi‘ which translates to ‘demon droppings. In an area of Mexico the plasmodium is fried and eaten by some of the indigenous people who call it ‘caca de luna‘ i.e. ‘moon’s excrement‘.
Other slime moulds have quite different forms. From a distance Ceratiomyxa fruticulosa is no more than a white splash on rotting stumps and logs, but closer inspection reveals an intricate architecture of miniature icicles. When it first appears Stemonitis axifera resembles a collection of small shiny beads. These gradually elongate and change colour before transforming into a brown fluffy spore-bearing mass. The fruiting body of Lycogala epidendrum, whose common name is ‘wolf’s milk’, are 3 – 15mm orbs of pink, red or orange which gradually change to pinkish grey.
What really got me hooked was finding a colony of exquisite 4mm fruiting bodies resembling tiny deep purple mushrooms that were scattered along the trunk of a dogwood tree (Pomaderris apetala) that had been lying on swampy ground for years, possibly decades. After checking a few websites the distinctive appearance of the slime mould made it easy to identify as Arcyria denudata.
I replaced the slime mould in a shady spot and planned to make regular visits to record its progress. As luck would have it, there was another Arcyria species about a metre away that I could also monitor.
I have learnt quite bit about slime moulds since that encounter with the purple Arcyria. For instance, slime moulds are apparently very sensitive to disturbance (they don’t like rough handling, but they don’t seem to mind loud exclamations of delight on being discovered!) and although a few of the A. denudata fruiting bodies on the sodden dogwood matured, I lost track of most of them and presume they did not cope well with being moved. Another mistake I made was photographing the very early stages which can be similar in different species. For example, many fruiting bodies first appear as bright yellow plasmodia, or a collection of small beads or stalked cylinders of jelly. It is only when these mature that their identifying features become obvious. However in many instances, as with fungi, microscopic examination of spores and other structures is needed for identification.
Surprisingly, there have been only about 1000 species of slime moulds recorded worldwide (in comparison, there are believed to be approximately one million fungi). They reach their peak of abundance in temperate forests and can be found on living and dead trees, rotting logs and other coarse woody debris, leaf litter, herbivore dung and bryophytes. There is even one record of a slime mould growing on a living lizard! The lizard Corytophanes cristatus is a cryptic species found in the forests of eastern Honduras. Its ‘sit and wait’ foraging strategy involving periods of immobility meant that a slime mould Physarum pusillum could colonize its body. This lizard, which also occurs in Mexico and Costa Rica, is the only vertebrate reported to have a plant (a liverwort, Taxilejeunea sp.) occurring on its body.
I was under the impression that the fruiting bodies, many of which are only millimetres high, were delicate ephemeral structures, but some stay around for some time. When you know where to look, you can see quite a few! For instance, in the forest near home I have found numerous old fruiting bodies inside old stumps or in hollow logs. One had been there long enough to have a growth of leafy liverworts on its stem.
It is not only their sudden and sporadic appearance that is fascinating, but also the fact that in their early stages of their life cycle they share some characteristics with animals – i.e. they feed and move about -, while their reproductive stage is similar to that of fungi – i.e. they produce spores.
Acellular slime moulds have two different trophic (feeding) stages. The spores germinate into individual, soil-dwelling, single-nucleus, sometimes flagellated amoebae. The word amoeba comes from the Greek amoiba: to change. It alludes to their ever-changing shape, a result of the expansion and retraction of temporary protrusions on their body called pseudopodia.
The amoebae feed on bacteria and other organic matter, and then divide in two – thus their population increases. Two compatible amoebae fuse to form a zygote, a process that involves the fusion of the protoplasm and the fusion of the nuclei. The diploid zygote feeds, grows and undergoes repeated nuclear division to develop into the plasmodium (pl. plasmodia).
The plasmodia are a single cell with multiple nuclei encased in a thin membrane. Because they can move through very small openings of a few micrometres they are able to exploit the microhabitats within decaying wood. There they feed on bacteria, yeasts, algae, cyanobacteria and fungal hyphae and spores. Eventually they move to the surface of the substrate to form fruiting bodies. This transformation is probably triggered by exhaustion of the food supply, and/or changes in moisture, temperature and pH. Wind disperses the spores in most species although invertebrates undoubtedly also play a part in this.
If conditions are unfavourable plasmodia have the ability to transform to a hard structure (sclerotium) and revert to a plasmodium when favourable conditions return. Similarly, amoeboid cells have the ability to change to microcysts and back again. Sclerotia and microcysts can remain viable for long periods; a strategy that probably ensures their survival in arid and other hostile habitats.
Although slime moulds are usually associated with moist conditions and are most often observed after a bout of rainy weather they are by no means confined to wet habitats. During an expedition to the northern Simpson Desert in 2007, substrates were collected from the Hay River region and taken back to incubate in the lab. Thirty-five species were documented including nine species not previously recorded in Australia. 41% of the species found during the expedition, including one that is considered rare, are also found in the desert of Western Kazakhstan, once again reflecting their cosmopolitan distribution.
Most slime moulds are not slimy, nor do they look like mould; rather, many are exquisitely shaped and quite beautiful. My search for slime moulds continues and while looking for these tiny organisms I have encountered so many other fascinating things. Rotting wood, stumps, logs and leaf litter abound with life!
Reference citation available on request
Sarah Lloyd is the author of Where the Slime Mould Creeps: The Fascinating World of Myxomycetes. To learn more, visit:
Where the Slime Mould Creeps: The Fascinating World of Myxomycetes
If you like to think of Tasmania as the West Island of New Zealand, then perhaps you might enjoy thinking of those islands as the Eastern Isles of Tasmania. However, despite the cultural and botanical similarities, the geology and landscape is something different altogether. The South Island of New Zealand never fails to impress…
Tasmanian nature photographer and regular TG contributor Arwen Dyer recently spent a month photographing Aotearoa/New Zealand, exploring snow-capped mountains, rainforests, lakes, limestone arches, wild coastlines and more. While in NZ, Arwen was an Artist in Residence at the Living in Peace Project. The opportunities in NZ allowed her to create images for her global project called “Celestial Archipelagos”. The next part of this project involves an Artist Residency in the Arctic Circle.
In order to complete this adventure, Arwen has launched a crowd-funding campaign.
Please consider making a pledge:
To the untrained eye it is possible to mistake certain flowering plants as mosses. Tasmania has a few examples, particularly some of the alpine bristleworts, which are small and turfed and even produce flowering stalks that superficially resemble moss capsules.
Much less likely is it for mosses to be mistaken as flowering plants, but yet, this was exactly what happened to a certain Australian moss by the name of Gigaspermum repens.
G. repens is a moss I had always wanted to see but Tasmania was not the best of places to be looking for it as it more typical of bare dry soils. This spring I was most fortunate to stumble on a small population near a rock outcrop on the summit of Mt Nelson.
The pale silvery quartz colour of the shoots were scarcely half a centimeter tall and reminded me of the ubiquitous Silver Moss (Bryum argenteum). Fortuitously, the plants I found were fertile, and in that state, there was absolutely no mistaking them. The fertile shoots were more than twice the size of the sterile ones and were, for lack of a better word, so pregnant.
Unlike most mosses which have capsules borne on a stalk held above the plant body, the capsules of G. repens were nestled among large modified leaves.
In this fertile state, plants are not dissimilar to minute flowers in bud. The capsule of Gigaspermum repens has a large operculum, or cap, which falls off when the capsules are ripe, leaving a great gaping mouth and exposing the characteristically large spores (hence ‘Gigaspermum‘ which means large seeds) that are just visible to the naked eye.
These large spores could be mistaken for seeds in a pyxidate capsule, a type of fruit in flowering plants like plantain (Plantago spp.) where the top falls off to release the seeds. The uniqueness of Gigaspermum has inspired bryologists erect a botanical family, the Gigaspermaceae, to accommodate it.
When the great 19th century plant collector Ferdinand von Mueller (1825-1896) found this plant, he allegedly thought it was a flowering plant belonging to the ice plant family (Aizoaceae) and named it Trianthema humillima.
Mueller was a first rate botanical collector and his incorrect description is no reflection of the lack of expertise on his part. Mueller was certainly aware of what mosses are. However, this episode does bear testimony to the morphological diversity that mosses can encompass, sans flowers.
In This Issue:
Hello and best wishes in midwinter,
There’s sunshine and snow visible out the window as TG 35 is compiled by our team of artisan platypus and master craft-devils.
This issue, we’ve got one hundred years of platypus research placed online in a collaborative archive – you can learn more about it in an update from Tina Schroeder and Mark Grant. We’ll also peer through the lens of Nick Fitzgerald at the strange colours in the sky above the Subantarctic Macquarie Island, and indulge everyone’s ongoing appetite for pictures of the Southern Lights.
Then, courtesy of the National Library of Australia, there’s a collection of historical photos from the early 20th century of underground locations across Australia and into Antarctica, with a fair few pictures by that paragon of Australian adventure photographers, Frank Hurley (His wonderful film on Tasmania, Isle of Many Waters, is also worth searching for back in Issue Five). Finally, we join Norm and Dawn by video on their sailboat tour across Bass Strait, and get a glimpse at island life on King Island.
You’ll surely enjoy reading them as much as we enjoyed gathering them!
Special update: National Science Week is soon happening around Tasmania, and there’s a great number of events going on to get you thinking about the natural world and the scientific endeavour. Have a look at their event-finder schedule online, and do get involved. We’re especially excited about two upwards-looking events:
In Ulverstone on the North Coast: The inaugural TAStroFest – Tasmania’s Astronomy Festival – is running from Saturday 1st August to Monday 3rd. There’s guest speakers, astrophotography workshops, evening sky viewings, science shows, telescope workshops AND an indoor planetarium! Learn more at tastrofest.wix.com/tastrofest
In Hobart: Aurora Australis & Night-Sky Festival – is taking Friday 7th August to September 03. It was great fun two years ago, and is set to be even better this year. There will be night sky photography workshops, lectures on understanding and predicting the aurora, and more. If you come along to the The Tasmanian Night Sky Photography Awards at the Wild Island Gallery, I might see you there. Learn more at www.auroraaustralistasmania.org
All the best,
More than 100 years of platypus observations for 277 waterways across the breadth of Tasmania are now available for download via the Terrestrial Ecosystem Research Network’s Eco-informatics’ ÆKOS data portal. The acronym ÆKOS stands for the Australian Ecological Knowledge and Observation System – they’re online at aekos.org.
Mucormycosis, caused by the fungal pathogen Mucor amphibiorum, has infected Tasmanian platypus for almost three decades. The disease causes skin lesions, morbidity and mortality. The Tasmanian Platypus Survey was conducted in 2008 and 2009 and aimed to
The scientists responsible for collecting and compiling the information were Nick Gust and Josh Griffiths. The 2008-2009 live trapping surveys were undertaken to determine the spread, prevalence and persistence of the disease. In addition, demographic (sex, age), morphometric (body size) and health and moult condition of captured individuals were assessed. Furthermore, influences of mucormycosis on the hematology, plasma biochemistry and other indicators of health in platypus were investigated.
Methods included live trapping across three categories of waterways: those that were historically affected by mucormycosis, those that were possibly affected and those outside the known distribution of the disease.
Over 200 platypuses were caught and microchipped, measured, sexed and examined for health and condition indicators. These indicators included Tail Volume Index, fur moult status and evidence of parasites, and ulcers caused by mucormycosis.
The Tasmanian Platypus Survey dataset has been submitted into ÆKOS by the Tasmanian Department of Primary Industries, Parks, Water and Environment (DPIPWE) and contains historic records from 1901 to 2007 that were compiled and analysed to run a comprehensive survey across Tasmania and King Island between 2008 and 2009.
Open-access via ÆKOS is, for the first time, enabling the general public and the ecosystem science community to view and download site data on platypus observations, collection methods and the relationship among observations.
The addition of the Tasmanian Platypus Survey to the ÆKOS data portal not only provides increased accessibility to the data set for researchers, but also contributes to the enduring knowledge base for this precious creature.
This is the first data set that DPIPWE has worked to make transparent within the ÆKOS Data Portal. Following its successful integration, the Agency is enthusiastic to identify further data sets that may be suitable for the ÆKOS Data Portal. The Agency is also working to integrate the Tasmanian Platypus Survey within their State information management system, the Natural Values Atlas.
In April 2015 I travelled to Macquarie Island on the Aurora Australis, the research vessel named after the atmospheric phenomenon. Auroras occur when solar winds interact with the Earth’s magnetic field and are most common around the equinoxes. Auroras were seen on several nights during the two week science and resupply mission to Tasmania’s subantarctic outpost, 1500 km south-east of Hobart.
On our second night on the island we reached a small ‘googie – field hut field hut late in the afternoon, shortly before the cold southerly airflow brought a rapid dusting of snow down to sea level. A couple of hours later, after dark, the clouds cleared and the air was unusually still. The sky was filled with swirling white beams and shimmering curtains of otherworldly neon green. Having previously only seen a couple of faint auroras in Tasmania I was unprepared for the intensity and dynamism of this display.
Auroras are most often seen in polar regions because they occur in an ellipse around the magnetic poles of the Earth. At mid-latitudes, such as in Tasmania (40-42°S), the Aurora Australis is therefore seen in the southern sky. But at higher latitudes such as Macquarie Island (54°S) you can be south of the aurora, depending on how far north it happens to extend. So it was strange to see the ‘Southern Lights’ in the northern sky! At Brothers Point on the east coast of the island a large beam extended overhead from behind Mount Tulloch to the west to near the eastern horizon over the ocean. It frequently played across the northern sky over Sandy Bay, but was not visible in the south.
At its brightest it was similar to the light of a full moon, illuminating the fresh snow in an eerie way. After an hour or so of watching the aurora ebb and flow another snow squall approached from the south and it was over. All of these images are 30 second exposures so they are slightly more blurred and more colourful than what is visible to the eye.
The National Library of Australia has compiled and shared a wonderful collection of public domain historical photographs of caves and hidden spaces throughout Australia. You can learn more about the book, Underground Australia written by historian Michael McKernan, at the NLA Bookshop.
If you’re on your way to Tasmania for an adventure in the farthest south, there’s several ways to arrive. Most people arrive by ferry or airplane…but wouldn’t sailing be more relaxing? Join Norm and Down through their DIY Travel Documentary as they approach King Island