Shell Sand on Herm

Image showing size of small seashells in shell sand from Herm in the Channel Islands

The sand on the Island of Herm, which is one of the Channel Islands, is mostly made of shells and shell fragments. A good place to examine the sand is Belvoir Bay where waves and currents wash shells ashore and break them up. The small cove lies at the foot of modest cliffs of Herm Granodiorite with xenoliths; and eroding rocky outcrops strew the shore at the base of the cliffs. Hollows and crevices in these rocks are filled with coarse shell sand containing many intact little shells of both bivalve and gastropod molluscs. Even minute sea urchin tests survive. I took a handful of the sand home to photograph against a scale, and compare them with some mature-size shells from the same beach and nearby Shell Beach. I have fond memories of visiting the island and collecting shells there forty years ago.

Seashore Goodies

I thought these colourful seashells, pebbles and seaweeds in their little bowls looked good enough to eat!

An Oyster Shell with a Black Pearl

Oyster shell with attached pearl

I found this shell on Rhossili Beach. Oyster shells often wash ashore there. The European Flat Oyster used to grow in abundance around the Gower Peninsula in South Wales and was commercially fished until about the 1940’s when stocks declined to such an extent that it no longer remained a viable proposition. They are presently trying to re-introduce the oyster fishery.

Fresh shells brought up by the tide would seem to indicate that Ostrea edulis still lives and breeds in the locality. The older shells have evidence that they have been around for a long time, possibly decades. Many are very thick showing that they lived for a long time. Commercially fished or cultivated oysters are usually cropped at three or four years before the shell has achieved its maximum growth and are therefore relatively small and thin. Left undisturbed, O. edulis can live for fifteen years or more. However, after a certain time, the diameter of the shell more or less ceases to increase and the animal’s energy is concentrated on thickening rather than widening the shell.

The longer the oyster lives, the greater the possibility of its shell assuming unusual shapes and abberations. Some of the mis-shapes result from the animal’s defensive reaction to infesting or encrusting organisms on or in the protective shell. Occasionally, irritation of the fleshy interior by foreign objects causes changes in the way the shell is laid down by the internal nacreous layer. This is the way pearls are formed. You may be surprised to learn that commercially fished pearls, and cultivated pearls, do not actually come from oysters. The Pearl “Oyster” – is a mis-nomer. It is in fact a Pearl Mussel. The Latin name for the Pearl Oyster species (of which there are several) is Pinctada. and the species belongs to the Family Pteriidae a close relative of the true oysters – the Ostreiidae. When Julius Ceasar came to Britain with the invasion and extolled the beauty of British pearls, which he then exploited and exported back to Rome, he was referring to pearls from freshwater mussels Margaritifera margaritifera (Linnaeus).

It is not common to find pearls in true oysters like Ostrea edulis but they do occur. They are not considered to be as valuable as those from mussels and in some cases are prone to disintegrate with time. I have seen good examples in the museum at Colchester, Essex, which is an area reknowned for its oyster fishing industry dating back to at least Roman times.

Pearls as we commonly know them usually form as distinct separate bodies within the fleshy mantle of the oyster. Occasionally, the pearls are attached to the inner nacreous layer of the shell. They can be attached by a short stalk. That is what we have here in this beach-combed oyster shell. The “pearl” is attached to the inner surface of the right valve of the shell next to the pale kidney-shaped adductor muscle scar. [The strong adductor muscle joins the two valves in life and is used to close the shell when necessary. The default position of the oyster is to have the valves open and apart and it is automatically kept in this position by the ligament at the umbonal or hinge end of the shell.] The black colour of the pearl and the shell itself is the result of spending a considerable time buried deep down in anaerobic sediments. Black oyster shells are common on Gower beaches.

Still Life Studies

Some still-life studies of white or cream-coloured natural objects on a black background: showing rounded white chalk pebbles from the Dorset coast in England; ribbed cockle-like bivalved seashells from Queensland in Australia; and a piece of bleached white coral skeleton washed ashore from the Great Barrier Reef.

Beachcombing at Ventry

Seashells, seaweed, and mermaids purse washed up on a sandy beach

Notice board at Ventry BayThe wide sandy beach at Ventry lies on the south coast of the Dingle Peninsula in Ireland and is home to a small harbour where boats leave for tours of the Blasket Islands, and it also marks the route of an ancient pilgrims’ way. According to the sign posted in the car park, the Saints’ Road (Cosán na Naomh) starts here in Ventry (Tráigh Fionnetrá) and finishes in Baile Breac at the foot of Mount Brandon over 18 km away. It is today waymarked by the symbol of a monk, and is thought to have been in existence for over a thousand years.

Waymarking for The Saints' RoadThe notice says that “In Old Irish literature, this beach was the scene of a somewhat mythical encounter known as Cath Fionntrá (the battle of Ventry) in which the great hero Fionn Mac Cumhaill overcame the Emperor of all the World except Ireland, Daire Donn”. Now all is calm on the beach with the only sign of struggle being that of the sea against the land. The sand is strewn with pebbles, shells, and sea weed; while the dunes are protected from erosion as in so many other places these days by the placement of large boulders (a structure known as rip-rap).

Sea Lettuce seaweed washed up on the sand

Dendritic drainage patterns on a sandy beach

Black scallop shell with gutweed on wet sand

Seaweed washed up on the sand

Assorted seashells and mermaid's purses wahed ashore on a sandy beach

Oyster Thief seaweed washed up on sand

Small jellyfish washed up on the sand

Razor and top shells with sea noodle seaweed on sand

Worm cast on a sandy beach

Dendritic drainage patterns in the sand with red pebbles

Sinuous drainage patterns in the sand on the beach

Otter shell and eel grass washed up on a sandy beach

Broken whelk shell on wet patterned sand

Seaweed and seashells on a sandy beach