Bluey: an exquisite sky-blue crab

To be honest, I have rarely found one so solitary, so perfectly formed—and so desperate to have its picture taken—than this exquisite little sky-blue soldier, sitting in splendid isolation at low tide on the [St] George River sand bank. I am encouraged by the slow but, I think, definite increase in the neat, round ‘holes’ and heaping piles of carefully swirled sand that have been appearing over the past few months … hopefully an indication that a community of soldiers may be taking hold. They are beautiful little crabs, and I, for one, would welcome a new colony to establish in the George’s small, secluded estuary … though, perhaps, they have always been there and I have been less than observant.
Mictyris platycheles, more commonly known as the soldier crab, is typically found in large, dense aggregations on coastal sand flats, with singletons, such as ‘Bluey’, being an unusual find. However, as these little guys are not usually found pottering around on their own, my fingers are crossed that ‘Bluey’ may turn out to be one of the progenitors of a blooming colony to come.

‘Bluey’ has a range that extends from the Bay of Bengal in the west to Japan in the north and Tasmania and the Victorian coast in the south [see: https://en.wikipedia.org/wiki/Mictyris]. Soldier crabs commonly live in massive groups that move in such a coordinated way that their description as an “army” is more than apt. Their armies are most active at low tide, when they emerge to feed before scurrying back to their home flat to burrow like a corkscrew to an average under-surface depth of 10-30cm. Their tell-tale calling card is a deep, round vertical hole 2-3cm across, and a neat pile of diggings nearby.

I will never forget seeing my first army of soldier crabs. It nearly [but not quite] diverted Susie and me when, on our honeymoon, we over-nighted at Merimbula while enroute to our awaiting Halvorsen cruiser on the Hawkesbury. At low tide, we watched the mudflats and sandbanks that line the lower reaches of Merimbula Lake heave with a moving carpet of red and blue as a myriad busy little soldiers popped up from their sand burrows and jostled each other in their race to the water line. It was nature at its best and was mesmerising. To think that a colony might form in a local Lorne estuary would add yet another marvel to our already marvellous coast.

However, while they typically live for 5 to 10 years, they are relatively fussy when it comes to their preferred water conditions and do not thrive in either pure saltwater or freshwater, but require a low-sodium, brackish environment. This may explain why they have not colonised the George’s sandbanks more heavily. In addition, they tend to stay buried in the sand if the water conditions are unfavourable, such as during high tide or when the water is too cold or too salty—factors that may explain their fickle appearances on the tidal banks.

It may also explain why they are rarely seen in the summer and autumn months when the river flows are low and almost all water in the lower reaches comes from the twice-daily tidal wash of seawater. However, from mid-winter and into spring, diligently dug little holes and sand piles begin to appear again as the winter rains restore a higher flow of fresh water to mix with the tide and create a more reliably brackish habitat.
These highly social creatures exhibit complex group behaviour, especially during feeding and burrowing. They graze on the sediment surface in large groups, the size of the group offers some protection from predation as there are both more eyes to spot potential threats and more targets for predators [ibis, egrets, toad fish and moon snails] to choose from … “so hopefully it won’t be me!”

Soldier crabs are truly exquisite. The Wikipedia website describes them as having “… small, blue, spherical bodies, with a red-purple patch on each side, and long, white, jointed legs” and that they “… feed on the organic material found trapped in the sand, using their pincers to scoop up sand and their mouthparts to filter out the edible particles”.
To see soldier crabs on the Otway Coast, one reference sight [see: https://tinyurl.com/yhtbj5ma] recommends that you: “… visit a sandy beach or mudflat during low tide … be still and observe from a distance to avoid disturbing them”. But as they are easily spooked and will ‘corkscrew in’ at the first sign of danger, perhaps the regular patter of dog feet on this dog-friendly sand-flat at the George is another reason why they are not often spotted and stay burrow-trembling and out of sight.
Fishermen will sometimes use soldier crabs as bait, though it is sad to think of such beautiful creatures being speared alive with a hook. Still, if a fisherman’s hook is not their nemesis, then a seagull’s or heron’s beak most likely will in this food-chain dependent world.
One fascinating fact about soldier crabs that highlights the remarkable capacity of the human brain to think laterally is their use in computing research, where they have been used as living replacements for billiard balls in experiments with billiard-ball computers [https://tinyurl.com/yu82mhh3].
‘Billiard-ball computers’ were first proposed in 1982 as an idealised model of a reversible mechanical computer based on Newtonian dynamics, where the electronic signals from a conventional computer are replaced by a spherical billiard ball bouncing back perfectly from a buffered wall in a frictionless environment. Think of the early personal computer game, ‘paddle tennis’, that many baby boomer parents would have played with their Gen X children, and you will get the idea.

In a series of experiments known as ‘Crab Computing’, “… swarms of up to 40 Mictyris crabs were herded down corridors by images of predatory bird shadows. When the configuration of the corridors causes two swarms to meet, they interact in predictable ways that simulate the behaviour of a ‘reversible logic gate’—a computing device that ensures that no information is lost.” As logical reversibility is an integral concept underpinning quantum computing, the humble soldier crab is making significant contributions to cutting-edge computer physics.

I can’t wait to find my next large soldier crab army-on-the-move and then, hoping not to score a direct hit on a little crab, lob in a tennis ball and watch a mass reverse gate effect in real-time as the crabs turn as one and scurry off in the opposite direction … or at least I imagine that may be how it would happen.

Meanwhile, I will wait in hope for another ‘Bluey’ to pop up and greet the day at the George.

John Agar
Feature Writer

A word from the chairman

Hello
Last Saturday morning I was privileged to join in the celebration of the 103rd birthday of one of our most senior citizens and local icon, Doug Stirling.
Doug was joined by 25 of his mates at the Men’s Shed to enjoy sausage rolls, party pies and home-made birthday cake to celebrate this special occasion.
After blowing out the candles on his cake (fortunately only three, 1, 0, 3), Doug spoke eloquently and unscripted about the importance of the Shed and Shedders in his life. He talked about the camaraderie and mateship that exists between Shedders and how his eyes light up when he sees a Shedder on the main street and shakes his hand. This reinforces the important role that the Men’s Shed plays in our community, welcoming men of all backgrounds, ages and skills.
Happy Birthday cobber Doug and continued good health!
*****

Last Monday the second Surf Coast Shire (SCS) affordable housing workshop was held with 14 community members in attendance, including two of our ward councillors. We finalised the problem statement and then turned our mind to solutions and how the $50,000 allocated by SCS to the project could best be spent. A number of options were considered but there was a clear favourite, which was to use the funds to investigate and identify suitable unused or sub-optimally used council or other public land to develop a small-scale, relatively low-cost housing development which would provide affordable rental accommodation for families and key and essential workers. The preferred option would ensure community “ownership” and control of the development in perpetuity.
This would involve feasibility studies which would address issues such as planning, design, funding, ownership structure and eligibility criteria. It was agreed that the group would meet again shortly to further develop these ideas. There was a strong feeling that, after discussing the issue of affordable housing in many forums over many years, “this time we can really make something happen”. Here’s hoping!
******

Last Saturday, Mother Nature made her presence felt with the wildest winds we have seen in Lorne for some time. Fortunately, there were no reports of major damage or injury, but it was certainly a testing time for the volunteers on the gates at the football and netball, with at least one marquee in danger of becoming airborne. Despite the weather, the Dolphins posted some good wins and for the first time hosted the under 9 Bellbrae Dolphins who played with great enthusiasm and endeavour, on a strategically shortened ground.
******
Congratulations to James Carew on being named a Life member of the Lorne Surf Lifesaving Club in recognition of his many years of service and commitment to the Club. Fittingly, the Club’s new IRB was named after James. Congratulations and thank you James.
Cheers and stay warm (or go North!)

Cheers 

Lorne Ward Events Calendar

August

2-3 Surf Coast Arts Trail, 10 am – 4 pm Joshua James Artist will be at Lorne Community Connect with a demonstration on Sunday 3 August at 11 am. Learn about the meaning behind Aboriginal designs and symbols.

3 – LAAC Winter Comp No 3. lines down after 6am, weigh in at the Lorne Aquatic and Angling Club at 12:30 followed by BBQ lunch.

9 – Lorne Dolphins Football and Netball V Western Eagles, at Stribling Reserve, juniors match from 8:45am, seniors at 2pm

16 – Surfcoast Wonderfalls Trail Run, Starting at Cumberland River/Lorne. Distances: 6km 13km 25km 42km 52km

23 – Lorne Dolphins Football and Netball V Simpson, at Stribling Reserve, juniors match from 8:45am, seniors at 2pm