Looking for Torbay Bonnets

 

I was very lucky to have been born, and brought up, in Torbay on the Devon Riviera coast, only leaving to go to University when I was 18 [1]. Although I now live in Hertfordshire, I enjoy my return visits to South Devon for a couple of days each year, and I’m hoping that 2021 will allow me to re-connect with my roots; COVID-19 having prevented travel in 2020.

Perhaps because I live inland, I have a strong love of coasts and I am drawn, especially, to the red sandy beaches of Torbay and the rocky outcrops of sandstone and limestone that are such features of the Bay and the adjacent coast. Every visit I make includes a walk along a beach and, unlike most people, my fascination is with the strand line of material left by the retreating tide. I started beachcombing nearly seventy years ago, when there was far less plastic and other refuse on the shore, most of that being discarded by ships, or coming through sewage outlets from around the world. My discoveries then were mostly of seaweeds (from which colonising sandhoppers scurried away when the weed was turned over) and the remains of marine animals, with shells and shell fragments being abundant. Sometimes, there was something unusual – a mermaid’s purse or a comb jelly – but mostly the remains were of molluscs, their soft body parts having been decomposed long before. The commonest shells were those of cockles, clams and razor clams and, usually, there were also good numbers of limpets, slipper limpets, winkles (of several species) and top shells. They intrigued me as a child, as I had such little knowledge of the aquatic world, except that acquired by exploring rock pools.

After a storm, the amount of detritus gathered at the strand line could be impressive and the number of shells, and shell fragments, washed up after the “big freeze” of early 1963 made one wonder just what had been left behind in, and on, the substratum of the shallow bay. Although I wasn’t aware of them at the time, among the shells would have been those of “Paignton Cockles” and “Torbay Bonnets”. I have described Paignton Cockles in an earlier blog post [2], but many readers will not have heard about Torbay Bonnets (also known as Fools-cap Limpets). These are extracts from a description written by Gosse in the mid-Nineteenth Century [3]:

The Fools-cap Limpets.. ..have the shell shaped like a somewhat high cone, with the summit a little produced, and turned over backwards. The surface is commonly marked with lines (striæ), and covered with a horny skin, which is sometimes invested with a short velvety down. The interior has no plate or partition of any kind..

..The only British species is commonly known by the appellation Torbay Bonnet; it also bears the names of Fools-cap Limpet, Cap of Liberty, and Hungarian Bonnet, all of which designations.. .. have an obvious reference to its form. It is a rather large shell, being frequently more than an inch and a half in diameter, and an inch in height. Its substance is rather thin, though strong, and somewhat translucent; its colour is a delicate pink, or flesh-white, though this is concealed, especially around the lower part, by an olive-coloured skin, covered with shaggy down. The interior of the shell is delicately smooth, and of the same roseate hue as the exterior.

The animal is usually pale yellow, with a pink mantle bordered with a fine orange-coloured fringe. The head, which is large and swollen, is tinged with brown.

Though generally distributed, The Fools-cap must be considered a rare shell. Torbay, as one of its familiar names indicates, is the locality in which it occurs in greatest abundance.

Gosse provides an illustration of the shell (above upper) that can be compared to a photographic image taken by Georges Jansoone (above lower). In the latter, note that the periostracum is missing, this being the coating of the shell that Gosse refers to. In both images, there is no animal present, just the shells that they secrete, the animals having a superficial resemblance to limpets and slipper limpets, the former being familiar to us.

Although Gosse refers to Torbay Bonnets as Fools-cap Limpets, they are very different to common limpets, although they share features with slipper limpets. Common limpets use a file-like tongue (the radula) to scrape over the surface of rocks to remove algae and biofilm and are mobile when covered by water, returning to their “home scar” should they live on rocks in the inter-tidal. Slipper limpets and Torbay Bonnets, in contrast, are sedentary and feed on tiny particles carried into the cavity of the shell by huge numbers of tiny beating hairs called cilia. The particles are then trapped on mucus and carried to the mouth for ingestion, the radula being important in this process [4].  

I began this post about Torbay Bonnets by describing my love of beachcombing in Torbay before I went off to University. There, I was taught about molluscs by Professor Alastair Graham and Dr Vera Fretter (the latter was my tutor) and they were acknowledged experts on British snails, like limpets, slipper limpets, and Torbay Bonnets. I wish that they were still alive, as I would love to chat to them to find out more about these fascinating molluscs (I didn't have so many questions when I was a student...). Their monograph on snails (see image below) remains a classic of scholarship and research and, just like Gosse, they made all the illustrations themselves. Few of us have these skills, and maybe they are not needed in the age of videography and the internet, but we can still enjoy beachcombing and the excitement of discovery along the strand line. I’m certainly looking forward to visiting South Devon in 2021 and I shall be looking out for Torbay Bonnets.

[1] Roger S Wotton (2020) Walking with Gosse. e-book.

[2] https://rwotton.blogspot.com/2017/11/the-legendary-paignton-cockles-and-some.html

[3] Philip Henry Gosse (1854) Natural history. Mollusca. London, Society for Promoting Christian Knowledge.

[4] C.M.Yonge (1938) Evolution of ciliary feeding in the Prosobranchia, with an account of feeding in Capulus ungaricus. Journal of the Marine Biological Association of the United Kingdom 22: 453-468.

[5] Vera Fretter and Alastair Graham (1962) British Prosobranch Molluscs: their functional anatomy and ecology. London, The Ray Society.