We have always had enjoyable holidays on islands, usually a good source of shells and shell sand, but when we decided to strike off into the unknown in 2005, we met with problems. In choosing our destination in Shetland as the Out Skerries, a very small group of islands ten miles to the east of mainland and perhaps five miles to the north east of Whalsay, there is little room for a range of habitats. Two small islands are linked by a bridge, with one shop on each, having probably less than seventy inhabitants in all. There are quite a surprising number of young families forming a close community. I think the main occupation is fishing.
Our house was beside the aircraft runway, with a linking gate. We could go through the gate to walk up the runway, except when a plane was due, shown by the arrival of the fire tender. As the planes are only eight seaters once or twice a day, there was little disturbance from them.
For our first trip we strode up the runway to the nearest "beach" consisting of very large rounded stones and a lot of limpet shells. There were no sandy beaches. Shell sand would be impossible to find, or would it? There were on that beach very many recently washed up Laminaria stems, with holdfasts, that were still damp and tight. I collected a few and on cutting them up found a treasure trove of sand, which I was surprised to see complete with small shells, besides the larger shells which do naturally live in such habitats, such as distorted scallops and saddle oysters. I did the sorting above a plastic bag to collect everything. I then washed it and left it in a plastic container to dry on the grass near the house. When I went out to get it a rogue seagull had upended the container. It was easy to pick up the larger shells but the sand and small shells were mainly lost in the grass, so I am unable to give a complete list, but I did try collecting again. All the beaches were similarly stony and lacked interesting shells, but on the cliff tops were a collection of larger shells including razorshells which must have been dropped by feeding gulls. How far can they be carried? There are no suitable habitats around, except possibly the small offshore island called Grunay, but you do get good views of whales (mainly Minke) and dolphins, from the hill.
I can only think that the holdfasts are attached to rocks in an area of swirling sand which gets washed in to the nooks and crannies, but how far they come I do not know. At least I was not entirely deprived of shell sand and it was a very interesting, different place to stay in for three weeks
The shells found were mainly typical holdfast dwellers. I found eighteen species listed as follows, with my thoughts on their likely habitats. Has anyone any further ideas please?
| Chiton sp | One worn valve. Probably washed in. |
| Tectura virginia | only two found. They may have been washed in. |
| Patella vulgata | Three found. It doesn't seem a typical habitat. |
| Helcion pellucidum | Thirty plus found. A typical holdfast dweller. |
| Gibbula cineraria | Five fairly large ones found. As they are intertidal, not a typical holdfast dweller? |
| Rissoa parva | Forty-seven found. As they lay eggs on weeds, they are to be expected. |
| Lacuna pallidula | Ten juveniles found. As their eggs are laid on weeds, they may be there for protection. |
| Alvania punctura | Fifteen juveniles found. They breed in weeds and holdfasts. |
| Onoba semicostata | Twenty-one found. They breed in weeds and silt. |
| Trivia sp | One worn shell . Probably washed in. |
| Hinia incrassata | Fourteen found, mainly (9) juveniles. They favour silty, weedy habitats. |
| Mytilus edulis | Twenty plus, juveniles there for shelter. |
| Modiolus modiolus | Sixty plus were found. Holdfasts seem a popular place for the juveniles to shelter. |
| Chlamys distorta | Three found. They are typical holdfast dwellers. |
| Heteranomia squamula | Forty plus. Typical holdfast dwellers. |
| Kellia suborbicularis | Fifteen plus found, mainly juveniles. They are typical crevice dwellers. |
| Turtonia minuta | Two single valves only, but they do inhabit crevices. Perhaps there were more I lost. |
| Hiatella arctica | Fifty plus specimens. Typical holdfast, crevice dweller. |