Vanlig strandsnäcka

More about the Common periwinkle

Returns home?

The Common periwinkle can be found in concentrations of up to several hundred per square metre in most beach environments. They are even common in estuaries, where freshwater mixes with salt water, because they are able to tolerate water with a salinity down to 10 parts per thousand. They can even be found on soft bottoms, but there must be a few hard objects such as rocks, piles, seaweed or mussel banks for it to flourish.
    It is quite easy to find periwinkles, when they creep along a sand bottom, they usually leave a 1 cm wide trail after them. Normally they move at a speed of about 1-2,5 m an hour, but if they are in a real hurry they can attain speeds of up to 5 m an hour. It is asserted that periwinkles return to the "hard bottom" after they have been out rumaging after food on the sand. You can test to see if this is true on the beaches you visit.

Glue their shell

The Common periwinkle combats dehydration very well. Periwinkles can survive out of the water for several weeks. They protect themselves by withdrawing into their shells and closing the aperture with a hornlike lid (operkulum) that is situated above their foot. When they have withdrawn into the shell, they have trouble holding onto the substrate. To avoid falling off stones and rocks into deep water, they secrete a mucus from their foot that hardens in the air. This "glues" the shell lightly onto the rock.

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Returns home?

Glue their shell

Can live in ice

Eats brittle algae

The shell protects

Worms in the shell

Pelagic larvae

Many are


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Bo Johannesson | Martin Larsvik | Lars-Ove Loo | Helena Samuelsson