Hill End to Spaniard Rocks & Back: Step-by-Step Part 8

Nearing the end of my walk now from Hill End to Spaniard Rocks and back again. The damp sand for hours exposed to air revealed in the oblique light intricate traceries of trails where small invertebrates had travelled around unseen on the surface to hunt for food. The tide had turned and was fast washing the shore clean again. First the light particles of wood and coal dust floated away and gradually all the other organic debris and flotsam were removed in order of weight. Just a few items left to go. Incredibly, a soggy soft pink toy starfish found itself marooned with a real starfish. I photographed it exactly as I found it. The red mooring buoy seen high and dry earlier in the day was now licked by the waves, along with paired prickly cockle shells, living whelks, a dead dogfish, and a wellington boot.

The sun was bright and the sea was dark blue and scintillating. Rows of sand ripples reflected the blue sky like a natural abstract painting. Such a view of the sea and sand in Rhossili Bay is one of the most uplifting I know.

I reluctantly left the water’s edge to negotiate the makeshift bridge across Diles Lake once more. This time I photographed the unattractive brown periphyton attached to the underwater rocks as well as the beautiful sunlit surface ripple patterns of the flow. While it was time for me to leave, others were just arriving with surf boards, impatient to immerse in the iridescent sea – now that must be some high on such an afternoon. I can’t wait to go back.

Baby barnacles on Rhossili rocks

It’s not just the birds, bees, and educated fleas that do it, the barnacles do it too ….. breed in springtime, that is! The results were there for everyone to see, with millions of miniscule baby barnacles smothering the rocks at Rhossili in Gower in early April.

Each newly settled barnacle measured just a millimetre or so. [It was at the limit of the camera’s capability to focus – so apologies if the images are not as sharp as they could be]. The baby barnacles develop from free-swimming cyprid larvae that are only 500 – 800  µ m long. The cypris is the final stage in the larval development of the acorn barnacle – following six consecutive stages as a nauplius larva.

The cypris looks a bit like a tiny clam or an ostracod with two large shells or valves hinged on the dorsal surface and open on the ventral one. Six pairs of fringed appendages used in swimming hang down from between the valves. The cypris has sense organs to detect suitable surfaces on which to settle. It also has small antennules at the head end which it uses to crawl over the chosen substrate before performing a head-stand and cementing itself into position on its back. Newly settled barnacles are referred to as spat.

The shell of the settled acorn (or sessile) barnacle has six over-lapping calcareous side panels making an approximately cone-shaped wall. The animal lives within this ‘box’. Four more hinged plates create a lid to the box that can be opened and closed. Once the new adult-like shell form is developed, the fringed swimming appendages or natatory cirri of the larva can then be protruded through the hinged lid plates to seive food particles from seawater.

[You can see more detail in the photographs if you click on the images once, or twice. If you look carefully, you should be able to recognise a few cyprid larvae with their smooth, glossy translucent shells, in the process of settling amongst the recently metamorphosed miniature adult forms].

The young barnacles settled on every patch of smooth, bare rock where it was available at the base of Rhossili cliff – but also on top of other living adult barnacles, on the old white calcareous bases left by detatched large Perforatus perforatus barnacles, on limpets, and on mussels.  Only the dog whelks with their variously coloured shells seemed mostly free from spat fall as they feasted on the mussels and barnacles.

 

Revision of a post previously published 18 May 2010

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Multi-coloured rock pool at Rhossili

Thousands of small multi-coloured pieces of flotsam plastic floating in a rock pool at Spaniard Rocks, Rhossili Bay, Gower, South Wales, UK (1) 

Thousands of small multi-coloured pieces of plastic flotsam floating in a rock pool at Spaniard Rocks, Rhossili Bay, Gower, South Wales. Even in the most beautiful of places, flotsam – particularly plastics – can be a problem. At Rhossili Bay, it is said that most of the plastic rubbish comes from as far away as South America as there is nothing but open water between these two places. Very little plastic rubbish is thought to have been generated by local visitors.

By some quirk of fate, small pieces of plastic seem to end up en masse at the extreme north end of the beach.  The way that  they have accumulated in small rock pools on Spaniard Rocks can be seen in these photographs.  However, even though this rubbish shouldn’t be here and it may affect the environment in a detrimental way, potentially damaging habitats for the native seashore animals and plants, there is still a beauty to be found in the juxtaposition of these brightly coloured pieces of floating flotsam against the pale neutral of the Carboniferous limestone; in much the same way that the bright splashes of orange-coloured lichen and yellow-flowered rock plants enliven the stone.

There is a related post to this article. See also Gulls’ gobbets on Rhossili seashore.

 Rock pool at Spaniard Rocks, Rhossili Bay, Gower, South Wales, showing multi-coloured plastic flotsam on the water surface (2) 

Revision of a post first published 13 July 2009

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Gulls’ gobbets on Rhossili seashore

Regurgitated Banded Wedge Shells and gull footprints on the sandy seashore at Rhossili, Gower. South Wales, UK (1)

It is not surprising that Banded Wedge Shells are easy pickings for hungry sea birds. In an earlier post, I described how they sometimes lie on the surface of the sand or sit partially buried/exposed on the lowest part of the shore waiting for the tide to come in.

As you walk along the beach at Rhossili on the Gower Peninsula, you can see the evidence for this kind of bird feeding activity. It seems that the gulls regurgitate or cough up the indigestible shells after they have gorged themselves on the bivalved molluscs. These ‘remains of the feast’ occur as small gobbets of matter scattered over the sandy seashore. Sometimes, the debris includes lucky escapees that have apparently survived the experience intact but mostly the shells are broken and the meat removed. In the photograph above the gobbet is clearly associated with the footprints of the bird.

Banded Wedge Shell fragments - Donax vittatus (da Costa) - regurgitated by a gull on Rhossili beach, Gower, South Wales, UK (2) 

Photographs 1 to 3 are examples of these gull gobbets with mostly Banded Wedge Shells. All three pictures were taken on 9th August 2006.

In photographs 4, 5 and 6 the gobbets are mostly made up of tiny pieces of the chitinous exoskeletons of small Crustaceans: probably including many Sandhoppers – Talitrus saltator (Montagu) – of which there must be millions on that beach. These shots were taken on 15th and 19th August 2011.

Images 7 and 8 were also taken this summer (19th August 2011) and show that the gulls had just been feeding on the young edible mussels growing on rocks, possibly nearby at Burry Holms and Spaniard Rocks. The regurgitated remains are solely mussels, many of which are intact and undigested. These gobbets contrast with some that I found on 6th August 2009 in which the mussel shells were mixed in with small pieces of coloured plastic (Photograph 9 – below). At that time, there were extensive deposits of plastic flotsam debris on the strandline near Spaniard Rocks. When I visited in  August this year (2011), the rubbish deposits appeared to have been tempoarily covered by a substantial depth of sand that had been washed up the shore.

A gobbet of Banded Wedge Shells and fragments (regurgitated by a seagull on Rhossili beach, Gower, South Wales, UK (3) 

A gobbet of Banded Wedge Shells and small crustacean fragments (probably Sandhopper chitinous exoskeleton) regurgitated by a seagull on Rhossili beach, Gower, South Wales, UK (4) 

A gobbet of Banded Wedge Shells and small crustacean fragments (probably Sandhopper chitinous exoskeleton) regurgitated by a seagull on Rhossili beach, Gower, South Wales, UK (5)

A gobbet of small crustacean fragments (probably Sandhopper chitinous exoskeleton) regurgitated by a seagull on Rhossili beach, Gower, South Wales, UK (6) 

A gobbet of tiny juvenile first year mussel shells (Mytilus edulis) regurgitated by a seagull on Rhossili beach, Gower, South Wales, UK (7)

A gobbet of tiny juvenile first year mussel shells (Mytilus edulis) regurgitated by a seagull on Rhossili beach, Gower, South Wales, UK (8)

What is intriguing about the gobbet shown below in Photograph 9 is its very different composition and constituents. Altogether much more solid and sub-spherical in shape with fragments of common mussel shells and seaweed predominating. Pieces of coloured plastic and translucent pellets are also present.

This gobbet of seabird’s feeding debris was found at the northern end of Rhossili beach towards Bury Holms and Spaniard Rocks. The rocks here are densely covered with mussels. A lot of plastic flotsam tends to naturally accumulate at this end of the beach. One of the rock pools was filled with small pieces of multi-coloured plastic.

Regurgitated indigestible food matter from a seabird on Rhossili beach, Gower, South Wales, showing pieces of coloured plastic and mussel shells (9) 

The Shorter Oxford English Dictionary’s definitions of gobbet include: a lump or mass; a large lump of mouthful of food; a lump of half-digested food.

Revision of a post first published 30 August 2009

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A net full of Dogfish at Rhossili

Scyliorhinus caniculus (L.): Dead Dogfish in a blue fishing net on the sandy Rhossili strandline, Gower, South Wales, UK (1)

Flotsam fishing nets on the beach are common. Usually they are empty. However, earlier this year I spotted a bright blue fishing net half-buried in the sand on the strandline at Rhossili in Gower and I was astonished to discover that loads of Dogfish were tangled in its mesh.

Fish in blue net:: Dead Dogfish in a blue fishing net on the sandy Rhossili strandline, Gower, South Wales, UK (2)

It is not possible to say at what stage the fish had been caught in the net – before or after the net was lost from the fishing boat. Fishing for Dogfish in UK waters is banned. Maybe the net was cut adrift when the nature of its catch was identified. We will never know. Sad to think of these fish first being either deliberately or accidentally caught, then cast away or lost, to end up dying on the seashore. What a waste.

Lesser Spotted Dogfish: Dead Dogfish in a blue fishing net on the sandy Rhossili strandline, Gower, South Wales, UK (3) 

Lesser Spotted Dogfish: : Dead Dogfish in a blue fishing net on the sandy Rhossili strandline, Gower, South Wales, UK (4)

Dead catch of fish in net on the beach: Dead Dogfish in a blue fishing net on the sandy Rhossili strandline, Gower, South Wales, UK (5)

Blue net with dead fish on the beach: Dead Dogfish in a blue fishing net on the sandy Rhossili strandline, Gower, South Wales, UK (6)

Revision of a post first published 5 September 2009

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Masked Crabs living at Rhossili

Living Masked Crab, Corystes cassivelaunus (Pennant), braced in the wet sand to meet the on-coming waves, Rhossili, Gower, South Wales (1)

This living small male Masked Crab, Corystes cassivelaunus (Pennant), with a carapace no more than 39mm long, was sitting with its hind legs dug well into the wet sand to brace himself against the incoming waves. The chelipeds or front legs are twice as long as the body in the male crabs. As the crab holds these long limbs up in front of him, the sun seems to shine right through them. The two long antennae are held together to form a long tube which helps the crab breath when it is entirely buried in the sand.

The carapace or shell has a fine granular texture. The colour can be anything  from pale red, through orange, to a yellowish-white. The markings and indentations on the back sometimes resemble a face; that is why it is called a Masked Crab.

The Masked Crabs shown in these photographs were engaged in some kind of purposeful behaviour, the meaning of which I am uncertain. They were at extreme low tide level just as the tide was turning. They dug their rear end into the sand and faced the sea with their front legs (chelipeds) held up bent before them. It seemed as if they were bracing themselves to meet the impact of the incoming waves. When the waves struck, the crabs rolled over and over backwards in the water, until the wave retreated again. This had the effect of moving the creatures slowly but surely higher up the shore. It seemed a deliberate manoeuvre but I do not know the purpose of the action.

They are a very common species of British seashores where they like to live on soft, sandy bottoms from Low Water Spring Tide down to 90 metres under water. Seeing these delightful seashore creatures alive and in action was a real privilege. More frequently, it is the empty crab shells that are seen on the strandline. I will post some photographs of these later.

Living Masked Crab, Corystes cassivelaunus (Pennant), braced in the wet sand to meet the on-coming waves, Rhossili, Gower, South Wales (2)

A living male Masked Crab, Corystes cassivelaunus (Pennant), on its back in the wet sand after being hit by a wave, Rhossili, Gower, South Wales (3)

A living Masked Crab, Corystes cassivelaunus (Pennant), seen through the clear, sun dappled, rippled water as as the tide washed over it, Rhossili, Gower, South Wales (4)

The same living Masked Crab as shown above (Photo 4) after the wave retreated, Rhossili, Gower, South Wales (5)

Living Masked Crab, Corystes cassivelaunus (Pennant), bowled over backwards by an incoming wave, Rhossili, Gower, South Wales (6)

 Revision of a post first published 19 December 2009

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Decorated driftwood at Rhossili

Driftwood tree decorated with flotsam on Rhossili beach, Gower, South Wales, UK, June 2009 (1) 

Driftwood tree decorated with flotsam on Rhossili beach, Gower, South Wales, UK, June 2009 (3)There are lots of creative people around Gower. Yet again, I have come across an inventive way with flotsam on Rhossili beach. In June I was surprised to find a decorated tree where none should have been. Almost like a poor man’s Christmas tree. A dead driftwood tree had been hoisted up and secured upright in the sand with all sorts of brightly coloured flotsam festooning its branches. It looked so incongruous in the setting, yet provided a wonderful temporary counterpoint against the splendid backdrop of Worms Head and the seascape of Rhossili Bay.

Driftwood tree decorated with flotsam on Rhossili beach against a backdrop of Worms Head, Gower, South Wales, UK, June 2009 (2) 

Revision of a post first published 21 July 2009

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Sailing by Rhossili Bay

By-the-wind-sailor chitinous float, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (1)

The sun shining on flotillas of miniscule boat-like objects wrecked on the glistening sands of Rhossili beach one cold January morning was one of the most amazing sights. These were the internal  transparent chitinous floats of By-the-wind-sailors, Velella velella (Linnaeus). Each one only 4 or 5 cms long, they lay stranded in small groups or on their own. The low early morning winter sun shone through them with their upright curving fin-like sails casting shadows on the sand and the floats glistening with reflected light.

Class Hydrozoa, Order Hydroidea, Suborder Athecata (Anthomedusae), Family Velellidae, Velella velella (Linnaeus) – a single North Atlantic pelagic species having a flat chambered oval translucent float with a triangular fin or ‘sail’ with a deep blue body. May occur stranded in large numbers on south-westerly coasts at any time of the year after strong long-lasting winds from the south or south-west.

By-the-wind-sailor chitinous float, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (2) 

In life these creatures live free-floating in the ocean. They float in vast swarms in the North Atlantic. They can be beached alive but mostly it is the dried floats that are found on the strandline. They are a type of  Hydroid and are distantly related to jellyfish. They are deep blue when alive and have series of tentacles encircling the underside of the float.

You can see in the picture below a group of these small floats alongside my own shoeprint in the sand which gives an idea of relative size. They can, however, grow upto 100 mm long.

By-the-wind-sailor chitinous floats, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (3)

By-the-wind-sailor chitinous float, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (4)

By-the-wind-sailor chitinous float, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (5)

By-the-wind-sailor chitinous floats, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (6)

By-the-wind-sailor chitinous float, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (7)

By-the-wind-sailor chitinous floats, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (8)

By-the-wind-sailor chitinous floats, Velella velella (Linnaeus), on the strandline of Rhossili Beach, Gower, South Wales, UK (9) 

Revision of a post first published 5 May 2009

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