Drifting

Sand, wood and bluebottles

The beach changed, remoulded by an overnight storm. I noticed it first near the fence that discourages people from going into the dunes. The posts were shorter, the bottom wire of the fence buried. The sand was deeper and had been piled up against the fence, burying the bottom 20 or 30 centimetres of it. As I walked along the beach, I noticed other changes. Rocks along the shoreline had disappeared under the deposited sand. Other things too. The bits of charcoal and ash that had edged the water’s furthest reach after the big fire a few months ago had gone, either washed away or buried.

Further up the beach I could see a bit of driftwood. I walked up to it. In close proximity its size dumbfounded me. Maybe eight metres long. A twisted, gnarled branch, bleached and barnacled. I think of the power of the storm that threw it onto the shore. The wood is smooth to touch, although deeply creased. Where did it come from? How far did it travel on ocean currents? How long was it buffeted and tossed? Questions that will remain a mystery. (Perhaps a DNA sample could be analysed to find out what it is and perhaps piece together where it came from. But some things are good left unknown, left as ideas to ponder and meditate on.) How long will it stay here before a wave picks it up and takes it back out to sea? Time may reveal that answer to me.

One morning I walk along the beach and at the far end, away from where we swim, the sand is strewn with bluebottles. Every couple of metres there is the familiar little blue sack and mess of tentacles. It’s tempting to call them jellyfish, but, although related, they aren’t jellyfish. Seeing them on the beach makes me nervous about swimming. I don’t like things that sting. I walk along, noting how prevalent they are, wishing I knew more about them. I have a quick, nervous swim, cursing my lack of knowledge about these common critters. Later, I fall into a rabbit hole of Googling about them.

The bluebottles we get here on the south coast of Western Australia are the same species that is found on the east coast of the continent. Physalia utriculus. They belong to a group of organisms called syphonophores and each bluebottle is a colony of individual polyps (zooids) rather than a single individual, but they are bound to live together and cannot exist apart. The polyp colony is made up of four different types of zooids, each with specialist functions. The sail is a single zooid (the pnuematophore), and then there are digestive zooids (gastrozoids), reproductive zooids (gonozoids) and, finally, dactyloids which form the tentacles and are covered with stinging cells. Ah, I knew it. Stinging cells. I was right to be nervous swimming. 

I read a little further and am somewhat mollified to learn that bluebottle stings, although often painful, are not fatal. Their cousin, the Portuguese man-o-war (Physalia physalis), is the more lethal critter, capable of delivering a very nasty sting. I also learn that bluebottles are rarely found in sheltered waters, which explains why I see them washed up on one end of the beach and not in the sheltered cove where we swim. 

Bluebottles live in groups, drifting on the ocean surface and feeding on fish larvae and tiny crustaceans which they snag with their tentacles. When they eat, the digestive zooids expand, becoming ‘all mouth’ in the words of the Australian Museum, swelling from 1-2 mm across to more than 20 mm. I find myself using my fingers to help visualise that change, holding my thumb and index finger a millimetre apart and then moving them to 20 millimetres apart.

But the coolest thing I find out about bluebottles is that their sails lean either to the left or the right, and this affects how they move with the wind. In any group of bluebottles, some will list left and some right, which affects where the wind pushes them. When a strong wind blows towards the shore, only those with a particular bent will be beached and the others will survive. Which I guess means the ones I see on the beach are all left-leaning or right-leaning. And the others of their population are drifting far away.

Walking along the beach of a morning before I swim takes on a new purpose. I look to see if there are bluebottles washed up. If there are a lot, my swim is short; a quick dip in the most sheltered corner. If I don’t see any, I swim more freely.

The driftwood branch becomes my turnaround point. It hasn’t been washed back out to sea. Yet. It remains immobile, but becomes less visible. The sand is swallowing it. I don’t know if the sand is rising and burying it, or if the wood is slowly sinking into the soft, wet ground. Perhaps a combination of the two. One day I walk straight past it without noticing, a combination of me being distracted and the driftwood branch no longer being such an imposing piece. Or maybe it’s that it has become part of the landscape and I am now taking it for granted, seeing without really seeing.

I turn around and walk back along the beach, wondering what else I have missed as I’ve walked along in a sleep, early-morning daze. A pair of sooty oystercatchers flies by low on the water, as if to remind me to keep my senses open, to be alive to this place.

See you outside,

Jill