Anyone for rockpooling? – 27th August 2022

A short blog with a difference.

I have been doing some work with nature charities, surveying rockpools in order to monitor variety and abundance of marine species (more details here). As part of this ‘work’ I am experimenting with high resolution zoomable photo-mosaics as a means of recording rockpools, but also, maybe, as a teaching/fun resource.

By clicking/tapping on this image, and zooming into the photo-mosaic that replaces it, and panning around, you can explore your very own rockpool.

Best results are with an at least reasonably high resolution screen and an not too slow internet connection. (Please let me know of any difficulties with using this, or indeed, thoughts in general).

Click on image to enter rockpool then zoom and pan around.

There are three types of sea anemone in this pool, one very easy to spot, the other two are a little harder.

(I may try to add a recording of shore sounds that plays while the image is open at some future date.)

Rock – 7th August 2022

(After a very difficult few weeks, helping look after a relative suffering the last stages of cancer. )

I don’t want to write for a few minutes, but rather sit here and soak in the peace.

It has been too long.  I am too tired to think.

I breath in the cool damp air, close my eyes, open them again and look to the sea.

A small flock of pipits rise and caught by the breeze arc away towards the hill. They are an analogy for something within, but I can’t put my finger on what.

The last time I came here this place was all wrong. Cold and bleak. Now it feels like life. Like breath. I would dissolve and seep into these rocks. Here. Forever. I have thought about this before, to be a rock on this hill. The calm being of it. Warm and chill. Rain tears on stone skin. Night sky. Day sky. Skylarks. A peregrine’s cry. In the spring a bird’s nest, a wheatear or stonechat’s maybe, at my feet, or behind my stone ear.

Am I irritated that a place can change so radically, from the negativity of my last visit, to the adoration of this? If I am honest, yes, but ridiculously – do we expect the desert traveler and the drowning man to see the same river?


I live in a beautiful place. But enjoying it is like going for a walk in a garden in which lurk many gorgons. Glimpse any one of them and you will be turned instantly to stone.

Enjoy the sunny days, but don’t think about climate change. Explore the sea but don’t think about the plastic pollution. Enjoy the sound of the river outside the door, forgetting how it flooded you that time and will surely do so again. Photograph the extraordinary wildlife, but keep out of focus its continually reported decline. Enjoy the woods on the valley sides but try not to see the bare branches of the dead ash.

So many lurking gorga, you need to walk wearing blinkers.

But still there is so much that is beautiful.


I took a trip to our nearest town a few days ago, to buy some groceries. It is a short drive, from the Cych valley, up and over, to the broader valley of the Teifi. A pleasant route along largely single-track roads between high banks covered in, depending on the month, snowdrops, primroses, daffodils, bluebells, wild garlic or foxgloves. The journey is something of a mild roller coaster, with the last few miles, once you start dropping down toward the river, reminding me of coming into land in a aeroplane. The slow descent, the engine quiet, coasting, occasional course corrections, and short bursts of power to momentarily recover height, even the turbulence of bumps in the road, all add to the illusion. Then, finally, a moment of stillness, before re-joining the world of people and purposeful activity.

The ostensible purpose of the trip, to buy the groceries, was soon completed by a few minutes shopping in CK’s supermarket. CK’s is the older supermarket in the town. The staff, some young and some older are generally cheerful and I much prefer it to the shiny new Co-op with its loathsome automatic checkouts.

My shopping done the real point of the journey could be indulged in; a coffee in the Cwtch cafe in the high street.  The Cwtch is one of the scruffier cafes in Emlyn, but the coffee is good, and, best of all, both the cup and milk start off good and hot and so the coffee can be enjoyed over half an hour or so, even if sat outside with a book, as I usually am.  Being a regular customer, I have earned the greeting of ‘the usual’ when I arrive, which is an additional small pleasure.

I enjoy these little excursions; a pleasant change of scenery and the feeling of people around me after the quiet and sometimes enclosing atmosphere of the Cych.  The little town is, of course, struggling, but today was Thursday, which is cattle market day, and so the car park and high street were busier than usual with the local farmers, with their 4 by 4s and trailers.  I do not want to get into the pros and cons of vegetarianism, but, albeit unthinkingly, I enjoy the presence of the cattle market in the heart of this little town. The sounds and sights it brings, the business and the feeling of purpose and connection with broader community. Not new or original observations maybe, but real to me.

This feeling of community has been a new thing for me. I have been living here for coming up four years now, but its novelty has not worn off.  It was not anticipated, though the friendliness of the people, as experienced on various trips and holidays, had always made an impression and was one of the chief reasons for moving here. 

I think I hadn’t known I was missing the ‘community thing’ until I experience it. I have been lucky in the past, nearly always living in attractive places, and hardly meeting anyone who was actively unpleasant, but this is different.  It is hard to pin down, but I characterise it to myself as a change of emphasis in human interaction.  Here, whenever you meet someone, in whatever capacity, you seem to meet the person first and the role they occupy second. There is an immediacy and a human touch to the contact, which, in turn, seems to bring about a corresponding openness and relaxation in me. I find myself chatting in a way I never did while in England.

As I sit, reading, looking around, I enjoy the snatches of Welsh that come my way from people talking in the street.  The Welsh language is supported at government level; not just taught within state schools, but actually prescribed as the language of teaching.

Because I enjoy it, I fear the loss of this local feel and culture. It is so vulnerable. Already areas I visit in Pembrokshire are becoming anglicised. One little community that lies at the end of a favourite walk of mine, made the news the other day for being, I think it was,  95 percent holiday homes. This area is not so honey-potish and so may be slower to change but I would hate to see this special quality go.

Of course, as an incomer myself, I am, to some extent, an agent of the very change I fear. But then maybe there is more than one way of incoming to a place. I hope I come with respect and humility and an appreciation of what is here.

It is soon time to head back. It has recently rained and I catch glimpses of the distant Preselis through gaps in the high hedges as they catch the sun and look bright in the clean air. I realize again how beautiful they are and how lucky I am to have ended up here and what a huge opportunity it presents. But how do I express all that I would like to express? Time is short I know, which begins to add impetus, but still, I have no real idea.

Keep swimming!

The somewhat fuzzy photograph above, was taken, in a rush, at the end of a rockpool survey.  Looking at it back at home it wasn’t at all obvious to me what it was, or even that its subject was organic. More geological perhaps? Some sort of crystal growth maybe?  A cluster of stars on a piece of rock at the bottom of a rockpool. 

I would normally have reached for reference books or the internet to identify a new find, but this time I didn’t know where to start, so I took the easy route and appealed to Twitter, hoping one of the several expert rockpoolers I know to be online would get back with an identification. And, within a few minutes they did1..  Not geological but biological. Animal in fact. A specie of sea-squirt commonly known as Star Ascidian.  Hence the stars, of course.

I was pleased. A new entry for my growing rollcall of species found in the pools of this little north Pembrokeshire Bay2..  I looked up Star Ascidian online to get the proper scientific name and its scientific classification:

Common name: Star Ascidian

Scientific Name: Botryllus schlosseri

Kingdom: Animalia

Phylum: Chordata

Subphylum: Tunicata

Class: Ascidiacea

Order: Stolidobranchia

Family: Styelidae

Genus: Botryllus

I like these scientific names and classifications. I enjoy the feeling of learning and arcane knowledge they project. They conjure images of ranks 18th and 19th century amateur scientists grappling to understand the world around them, at a time when the balance between knowledge and mystery left room for such intellectual curiosity and simple enthusiasm. The problem is they pique my interest.  Like tips of icebergs, they hint at more below; hidden research, information and knowledge.  I find I need to delve further, and that one thing leads to another, so that what might have started as a chance finding of something curious in a rockpool, all too easily mushrooms into a much larger, sometimes even burdensome, investigation.

Whenever I sense this process starting, I am reminded of J.R.R. Tolkien’s beautiful short story ‘Leaf, by Niggle’, in which an artist, Niggle, becomes obsessively absorbed in a particular painting which seems to take on a life of its own.

“There was one picture in particular which bothered him [Niggle]. It had begun with a leaf caught in the wind, and it became a tree; and the tree grew, sending out innumerable branches, and thrusting out the most fantastic roots. Strange birds came and settled on the twigs and had to be attended to. Then all round the Tree, and behind it, through the gaps in the leaves and boughs, a country began to open out; and there were glimpses of a forest marching over the land, and of mountains tipped with snow. Niggle lost interest in his other pictures; or else he took them and tacked them on to the edges of his great picture. Soon the canvas became so large that he had to get a ladder; and he ran up and down it, putting in a touch here, and rubbing out a patch there. When people came to call, he seemed polite enough, though he fiddled a little with the pencils on his desk. He listened to what they said, but underneath he was thinking all the time about his big canvas, in the tall shed that had been built for it out in his garden (on a plot where once he had grown potatoes). “

I particularly that last line ‘on a plot where once he had grown potatoes’, presumably illustrating how the obsessive work on the painting displaced more practically fruitful activity!

Anyway, my little sea-squirt acted, for a while, a little like Niggle’s Leaf. I have sketched one of the main branches of its tree here and will add one or two more in a second blog shortly.   

The first thing I noticed was that the sea-squirt belongs to the Phylum Chordata. The ‘chord’ in Chordata refers to a primitive nerve chord that may run along a creature and from which the spinal column and backbone evolved. Chordata is therefore the phylum to which all vertebrates, including ourselves belong. 

Two things followed this; the first was I realised that although I had recorded many different species since I started delving into these rockpools, this was the first that belonged to this group.  How different this is to the land-based animal life we are all familiar with, where Chordata seem so dominant.  For example, all the mammals, including ourselves, amphibians, reptiles, birds, fish, snakes, lizards are all Chordata. I started to wonder why this difference is so marked, which led to reading read about disparate subjects such as why insects are small and how the average density of many animal bodies, including our own is almost the same as that of sea-water, which means that marine life doesn’t feel gravity in the way land animals do enabling the wonderful strange and delicate forms of rockpool life I had been finding.

Having learned that belonging to chordata implies a primitive spinal cord or backbone, I looked again at the photograph.  It was not at all obvious how this thing, which appeared little more than a smear of patterned jelly, could have a backbone or indeed would have any use for one. Turning to the formal definition of Chordata I read,

“Chordata: A phylum of the animal kingdom comprising all the animals that have, at some stage in their life, a notochord (a hollow dorsal nerve cord), pharyngeal slits, and a muscular tail extending past the anus. Includes the subphyla Cephalochordata, Urochordata, and Vertebrata (vertebrates).3.

The clue is in the second line; “at some stage in their life”.  It turns out that the sea-squirt starts out as a free-swimming larva, somewhat like a little tadpole, complete with a primitive, eye, tail and notochord and importantly, a very rudimentary brain, designated to controlling it’s motion.

After a brief free swimming (pelagic) period the tadpole attaches itself to a suitable substrate and metamorphoses into the attached (sessile) jelly form I found. 

This life-cycle, of pelagic larva to sessile sea-squirt, turned out to be more significant than it at first seemed. 

Evolutionarily speaking the story goes like this; Once Upon a Time (roughly 550 million years ago) there was a specie of tiny tadpole like creatures that spent their days swimming in the sea. Some of these tadpoles found that it took much less effort to cling to the rocks and wait for the food to come to them than to actively seek it out by swimming, while the others stuck with the original swimming about plan.  Each group became somewhat set in their ways and slowly evolved to become more suited to their adopted lifestyles.   

The group that stuck with the swimming, we could call them the pelagic group, went on to great things, or, even if we eschew this somewhat subject value judgement, at least went on to great variety and experimentation, as it is now believed, that these little free swimming tadpoles evolved to give rise to all the vertebrate life on earth, including, of course, ourselves. 

Things did not go as well for the sessile group. Nature discovered (through the usual method of ruthless experimentation no doubt) that once attached to its rock the organism no longer needed its tail, eye, embryonic spinal cord and backbone, or, for that matter its brain. These organs the sea-squirt evolved, in a process known as regressive evolution, to digest for the sake their protean content!

The element of black humour in this coupling of an organism ‘settling down’ with the loss of its mental faculties, has not been missed. The philosopher of mind, Daniel Dennett, draws a parallel to the process of a university professor obtaining tenure!

“ The juvenile sea squirt wanders through the sea searching for a suitable rock or hunk of coral to cling to and make its home for life. For this task, it has a rudimentary nervous system. When it finds its spot and takes root, it doesn’t need its brain anymore so it eats it! (It’s rather like getting tenure.) ” 4.

Professor Sea Squirt5

Different lines of investigation, including modern genetic analysis, indicate that the sea-squirt is the immediate ancestor of all vertebrates and therefore is considerably closer to humans than many other forms of equally unlikely looking life.  For this reason, among others, the sea-squirt has become the model organism for studying the evolution of vertebrates, including the origin and development of human hormone, nervous and immune systems.  The latter, among other things, providing a new range of chemo-therapy drugs6..

The above is a tiny sample of what investigations of the humble sea-squirt have revealed and are still revealing, but already I somehow felt the need to shake its hand, if only it had one.

Evolution of chordates showing the sea-squirt (Tunicates) as the ancestor of the vertibrates.7.

  1. Thanks to:
  3. For example:
  4. MLA (7th ed.) Dennett, D C. Consciousness Explained. Boston: Little, Brown and Co, 1991.
  5. Drawing by Paul Jackson. ©Randel McCraw Helms, 2018