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Baltic tellins

August 5, 2018

Colour variation in Baltic tellin shells


The Baltic tellin (Limecola balthica, but until quite recently known as Macoma balthica) is a small bivalve found between the tidelines of sandy and muddy shores, and especially estuaries across northern Europe. It is an infaunal species, meaning that the living animal is found buried within the top few centimetres of the sediment, however empty shells are a common find. The beach at Burnham-on-Sea in Somerset is typically strewn with them once you get below the strandline.

Baltic tellin shells on the beach at Burnham-on-Sea

Baltic tellin shells on the beach at Burnham-on-Sea

Their shells come in a range of colours, with white, yellow, orange and red forms found. Blue and purple shells may be stained by sulphides within the sediment. Typically, when mollusc shells show colour variation within a species, it may be due to visual predation, often from birds. The infaunal life habit of the Baltic tellin would seem to suggest that this is not the case however, and the different colour forms seems to coexist in the same locale.

I have found Baltic tellins (sadly without their pigmentation) in archaeological levels at the Walpole site in Somerset, and just recently noticed their shells within the mortar of the medieval gatehouse of Cleeve Abbey, suggesting a local muddy shore, perhaps the mouth of the Washford River, was used as the source for the sandy component of the mortar.

Baltic tellin shells in the mortar of the gatehouse at Cleeve Abbey

Baltic tellin shells in the mortar of the gatehouse at Cleeve Abbey

Autumn and the beginning of a year

November 19, 2017

Lichen and long shadows near Newton St Loe, November 2017

Aside from a five year break about a decade ago and an earlier period I can’t remember, I’ve spent all of my life in some way bound to the cycle of the academic year, in which renewal comes in autumn. This affects how I map out time in my mind. February 2018 is “this year” to me; September 2018 is not. This odd desynchronising of a mental calendar from the actual calendar is not unique to the education system however, and resonates with a more ancient and necessary organisation of time – the farming year.

“Farming” for me consists of a few pots on an inner city balcony – my autumn tasks were to plant garlic cloves, sow some early vegetables and clear a seemingly endless blizzard of plane tree (Platanus sp.) leaves to deny shelter to troublesome invertebrates. For a traditional farmer though, autumn is also the season of renewal. For arable farmers, the harvest will be ending (save for crops like sugar beet that are harvested into December), and preparations beginning for that of next year. The land will be manured and tilled and winter wheat, barley and oats may be sown. For livestock farmers in wet areas, cattle may be moved onto winter fodder. Sheep will be mated for spring lambs.

For farmers, and perhaps especially farmers in pre-mechanised societies of the past, difficult decisions need to be made in autumn. Sowing crops in autumn is a gamble. If it pays off it allows a staggered harvest, and light frosts may induce more productivity in crops. Heavy frosts, however, can destroy the crop. As Peter Reynolds noted in his excellent Shire Archaeology book Ancient Farming (1987), fields selected for autumn-sown crops are likely to be those away from high plateaus and valley bottoms to avoid the most severe frosts.

Livestock farmers would have had to turn their attention to culling the herd or flock. Non-breeding stock – young males and old females – are a drain on winter resources. The cull would necessitate a flurry of activity butchering, and salting or smoking meat. Grazing would be eked out as long as possible to conserve winter fodder – if this was mismanaged, further culls would likely follow. For a farming society, autumn is logically a season of renewal, the end of one year’s work and the beginning of another.

Interview: 2 years of Open Quaternary

July 25, 2017

Our open access journal Open Quaternary is now two years old (see So we started a journal…). To mark this anniversary, our publishers Ubiquity Press interviewed Suzanne Pilaar Birch and I, which you can read here:

Experimenting with social video

June 5, 2017

I really enjoy spending some time at the weekend exploring different aspects of current affairs around the world through the short videos posted by AJ+. Obviously, these kind of social videos have great potential for education, and I think I’d like to try incorporating them into my Sustainability module at Bath Spa next year. To get used to working on them though, I made an attempt this weekend using a site I studied as part of my PhD research, Ceardach Ruadh on Baile Sear in the Western Isles of Scotland.

I hope you like it!

By-the-wind sailors, beached by the wind

April 29, 2017

Back in March, we walked along the beach at Woolacombe, Devon, the morning after a stormy night. The night before had been spent in Ilfracombe, watching tall spray crashing against the sea wall, our senses woken with the energy that only a storm beating can impart.

Woolacombe was still and sunny the next day though, with fog hanging over the hills above, lending an island quality to the town. On the beach, by the rocks, I photographed colonies of mussels, dense mauve blooms erupting from the folds of the grey rocks. The strand line of the beach held a rarer sight though, scores of by-the-wind sailors, Velella velella, driven ashore by the previous night’s storm, and oozing a deep blue into the sand.

Velella are free-floating hydrozoans, related to jellyfish and sea anemones, and are in fact a colony rather than an individual animal. In life they float on the surface of the sea, where a small rigid fin or sail catches the wind (hence the English name, by-the-wind sailor). Mass strandings are relatively common after strong winds on south western coasts in the UK, and also along the west coast of North America. The ‘sail’ is made of chitin, the same stuff as insect skeletons, and the beached colonies very quickly dry out and lose their colour.

Velella velella stranded on Woolacombe beach, March 2017