Beachcombing is an environmentally friendly way of collecting shells.
Sand is made up of small particles (between the size of pebbles and silt) of rocky material or shell. Wave action and currents move these particles and deposit them on the coast – forming sandy beaches.
Rock and Shells
Every sandy beach is unique, and the size and nature of the particles will differ – as will the slope and horizontal extent. Most sands are composed of a mixture of rock particles of varying size and colour and shell fragments. In some places the beach may be entirely made of bits of shell, and while this often make white sand other colours are possible. Pink Sands Beach (in the Bahamas) is an example of a beach with an unusual pink sand made from the shells of the Sea Strawberry (Homotrema rubrum) – a foraminiferan that lives on the reefs, while the white sand in the photo which illustrates this article is in the Outer Hebrides and is composed almost entirely of shell fragments.
Digging in Sand
Animals that live on sandy shores need to be able to burrow if they are to avoid being washed away, and most of them feed on plankton or organic particles. Birds are particularly important predators on sandy (and muddy) shores, but there are also a few burrowing molluscan predators such as the Necklace Shell (Euspira catena). At the top of the shore there are usually many land insects which feed on rotting material, in addition to a few specialist marine insects and the ubiquitous sand-hoppers.
Shell Collecting
The shells of dead molluscs that once lived near the beach will be washed up regularly, and this is a very good way to collect shells. The animals are already dead, and there is absolutely no environmental impact involved. Beachcombing, especially after stormy weather, will find the empty shells of molluscs that lived in deep water. They will not last long, so this needs to be a daily activity (but not an arduous one!).
Sand Castles
Children the world over love building sand castles, and one or two marine invertebrates (such as the Lugworm – Arenicola marina) also make an attempt. These worms spend their life in burrows under the sand, but give themselves away by regularly casting sand onto the surface. Sometimes the entire lower part of the beach will be covered with these little piles of sand, and beneath each pile there is a fat, juicy worm ready to be eaten by a bird or used as bait by a fisherman.
(The BBC has a very interesting web portal about the coastal habitat where it is possible to take a virtual tour and explore coastal wildlife in a series of 360° panoramas.)
Other articles by John Blatchford
