Invasion Of The Soldier Crabs


Remember this? December 2016, at the end of the sealed road on the far north east coast of Australia.

And that sign has bugged me ever since. If there is one thing guaranteed to make me want to do something it’s someone telling me I can’t do it. What lies beyond the end of the road? There’s a certain allure to venturing somewhere only a privileged few can go. That and the extra frission of excitement that comes from going off piste, deeper still into the wilderness.

Beyond the 4WD sign the Bloomfield Track continues to Cooktown on the Cape York peninsular. Building it was controversial. The proposed route took it through untouched wilderness sparking protests and blockades in the 1980s. When the road finally opened, in 1984, a more direct route to lessen its environmental impact resulted in some steeper sections where the track simply goes straight up one side of a hill and down the other. No gentle meanders! The road remains partly unsealed presenting something of a challenge in inclement weather. At the height of the wet season it’s often closed altogether.



Cowie Beach, The Bloomfield Track



The Donovan Lookout, Bloomfield Track

..where the World Heritage Daintree rainforest meets the World Heritage Great Barrier Reef. How could I not go? Before leaving England we contacted Mike D’Arcy (here) to arrange a 4WD tour. I have to tell you it was worth every penny. Sorry, Australian cent. Because as well as providing the wherewithal to take us beyond that sign, Mike knows all the best places to see.



Coconut Beach

This is fringing reef, coral reef butting right up to land. The corals higher up the beach, being exposed to air at low tide, are sadly long since deceased and the calcium carbonate structure which once provided their home is now smothered in algae. But you wouldn’t need to go too far out from here to find something recognisable as the Great Barrier Reef.



As at Cape Tribulation, a little farther south, Emmagen Beach hosts the sand bubbler crabs which so mesmerised me the last time I was up this way. You might remember the video from David Attenborough’s Blue Planet (here) and surely it’s worth another view?



Bubbler crabs feed by filtering nutrients out of the sand and then reforming the discarded grains into perfectly round pellets. These are deposited back on the beach in a characteristic fan pattern around each crab burrow.



As the crabs work, against the clock and the next high tide, the individual patterns merge creating a dense mass of sand pellets in great swathes across the beach. But could we find something even more spectacular? At Cowie Beach, on the Bloomfield Track, yes we could.



There are many iconic images of Cowie Beach. It’s a wild and natural place with mangroves growing between the low and high tide lines. This is of course crocodile country. You might even come across the occasional shark..



OK, I know it’s only a baby one. And you have to look hard for it. Because I only just caught it in time. But that’s a dorsal fin, honest.

Eat your heart out Jaws.



Mangroves on the beach



But there’s more.

All the literature I’d read and, indeed, Mr D’Arcy himself, suggested that if we were very lucky we might see some soldier crabs.

They have a number of distinguishing features, not least that they’re one of the very few crab species which walk forwards rather than sideways. They feed in much the same way as the bubbler crabs but with a crucial difference: they don’t like to work alone. No, these guys march across the beach in battalions.



Right turn Clyde.. here they are taking evasive action having seen me coming. Poor things.

If the perceived threat persists the group disbands and each individual legs it in any available direction. Crabs, after all, come well equipped in the leg department. As a last resort each one will abruptly turn itself into a corkscrew, diving and twisting deep down into the sand. In seconds it is as though they were never there.



But the farther we walked out across the beach the more crabs we saw. Suddenly the realisation that there were more than a few. There were thousands. If not tens of thousands. Armies of soldier crabs, everywhere. How lucky were we? It was a moment that will stay with me for a very long time.



Blue soldier crab (Mictyris longicarpus)



A handy reference for size.



Continuing up the track, the Bloomfield River.



And the Wujal Wujal (Bloomfield) Falls.

It’s the end of the dry season right now in Far North Queensland. In a few weeks time these falls will be seriously pounding. The only problem is, unless you have access to a helicopter or a drone, it’ll be a challenge to get to see it.. even in a 4WD. The river reclaims the road. Such is the nature of things in the remote bushland of Australia.



By now it was late afternoon and the light was fading. On our way back down the track we dropped in again on Cowie Beach.

The tide was returning and the soldier crabs had retreated back into their burrows. But the place is still totally surreal. As the beach is so flat and protected by the fringing reef there are no waves as the water finds its way back. It just seeps quietly across the vast expanse of sand, filling each furrow in turn. Every few seconds we need to take a step back. And there is utter silence. Not even a wisp of a breeze.