What can be found on the strandline #4 Shells

The strandline is the high water mark on a beach where waves dump materials which can later be found by discerning beach combers.

Winter is a brilliant time to go beach combing because the stormy weather tends to wash up interesting things onto the strandline more frequently and in greater quantity.

Shells

While beach combing in the strandline, you will likely come across a number of shells from different species of molluscs. These shells are most often empty as the animal inside has died and likely been eaten.   

The most frequently seen shell on Sussex beaches is the slipper limpet (Crepidula fornicata). This is an invasive species that was accidentally brought over from the US in the 19^th Century with a shipment of oysters. It is now widespread in the UK and out competes our native oysters and mussels for space. They are however, interesting creatures. They live in mating stacks of up to 12 individuals, and the limpet at the base of the stack will be the biggest and oldest and is always female. If this female dies, the next largest will turn into a female!

Other shells to look out for:

• Common limpets (Patella vulgata) shells are conical and are greyish white in colour.
• The common whelk (Buccinum undatum) is the largest sea snail found in the UK and can grow up to 10 cm in length.
• Dog whelks (Nucella lapillus) are smaller than the common whelk and can be variable in colour – you can find orange, white, yellow and brown individuals.
• The edible, periwinkle (Littorina littorea) is a small, dark brown or grey shell which looks quite similar to a land snail.

 If you do find shells on the beach, it’s important to remember that hermit crabs (Pagurus bernhardus) use empty mollusc shells as homes, so it’s best to leave the shells where you found them in case they are needed by a hermit crab.