Beachcombers Field Guide - Department Of Fisheries Western ...

Periwinkle
Mollusca – Gastropoda
Various species of
periwinkles – dark blue, black,
brown or grey – live on rocks in the
splash zone above the high tide mark.
They can survive for long periods out of
the water due to the horny, tight-fi tting
trap door, or operculum, which retains
the moisture within the shell. Periwinkles
graze mainly on microscopic algae
and diatom fi lms on rock
surfaces.
Photo: Michelle Dyer
Did you know?
Most periwinkles reproduce by
releasing egg capsules into the
water, which form planktonic
larvae before settling on the reef.