Sandy beaches are a direct result of the constant erosion of rock in the sea. Grains of sand are carried by waves and currents and are constantly being removed and deposited on the shore, as sandy beaches. By their nature, sandy shores are often very mobile and constantly changing, especially those on exposed areas of coastline. The shape of a beach (and the animals that live within it) can change within a few hours during stormy conditions. In sheltered areas, sandy shores may be more stable and home to larger, slower growing animals. Sand may even be held together by the roots of seagrass, helping to hold sand in place and creating an even more stable place to live.
At first glance, it is easy to assume that sandy shores are devoid of wildlife. Nonetheless, animals here have developed several physical features and behaviours to survive in this environment. Animals are distributed on the shore according to how quickly the sediments dry out at low tide, which in turn is dependent on the particles’ sizes and height up the shore. Most animals are able to live by living beneath the surface of the sand, most hiding away as the tide drops, with many emerging as the tide comes in to feed. Some animals (mainly bivalves like clams) feed with tubes opening above the sand to suck in water and filter out food from the water. Some (including worms and brittle stars) gather food from the surface of the sand with tentacles. Others (like snails and crabs) emerge from the sand when underwater and search for food. Finally, some animals (including many worms) continuously burrow through the sand seeking prey or removing food from sand particles.
Other creatures visit the shore at different times to make the most of the supply of food which it holds. At low water, this can include birds and mammals, whilst the returning tide brings fish seeking a meal. Visiting fish include the sand goby, sand eels and the lesser weever fish. These are joined by flat fish, like dab, plaice and Dover sole. Mullet, sand smelt and seabass are also common visitors. Land animals that visit the shore include rats and shrews feeding on the strandline, and of course birds like gulls, cormorants, waders and gannets, some of which are actually dependent on the shore.
- Sand on the beach is actually full of food, bacteria and microscopic, plant-like organisms called diatoms live on and among sand grains, providing food for the animals that live there.
- The speckled sea louse (Eurydice pulchra) emerges from the sand to feed as the tide comes in. Incredibly its emergence corresponds with its natural tidal rhythm even when kept in captivity!
Some key species commonly found around the British Isles
Lesser Weever Fish (Echiichthys vipera) – lives buried in the sand in pools and just below low water and gives a painful sting if you happen to step on it bare foot
A sand hopper – (Talitrus saltator) – common all over the UK usually found at the top of the shore among the strandline
Lugworm (Arenicola marina) – at low tide, you can see the sand castles left by the burrowing worms, which live in a ‘U-shaped’ burrow.
Banded wedge shell (Donax vittatus) – takes 5-6 seconds to burrow using their muscular foot that inflates to work as an anchor
Masked crab – (Corystes cassivelaunus) – Lives buried just below the surface of the sand, using its specially adapted antennae as a ‘snorkel’ to ensure a clean supply of water.
Brown shrimp – (Crangon crangon) – is common on sandy shores around the country, it is well camouflaged against sand an buries itself quickly to hide just beneath the surface.
South claw hermit crab – (Diogenes pugilator) – is a small south-western hermit crab, common on sandy shores, it has a distinctively large, pale left claw.
Sea potato – (Echinocardium cordatum) – is a type of sea urchin, found on sandy shores around the British Isles, its fine spines give it a hairy appearance.