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Distribution in scandinavian waters
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Maximum length: 1,8 cm.
Appearance: The shell can vary greatly in colour, shape and pattern,
but the spire is very flat and usually has a yellow, olive-green or
brown colour. The soft parts are uncoloured to black. Coloured bands
on the tentacles are rare.
Depth: 0-5 m.
Environment: One of the specie creeps and feeds mainly on knotted
wrack. The other specie is found mainly on bladder
and toothed
wrack, but primarily eats microalgae that grows on the surface of
the seaweed. Empty flat periwinkle shells are often found on
the beaches.
Misc: In its most northern areas of distribution, certain individuals
of one specie have long spires and bear a certain resemblence to the
rough periwinkle.
Classification: The flat periwinkle belongs to the
periwinkle group (mesogastropoda) under the molluscs.
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