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  • Gastropod – a large taxonomic class of invertebrates that includes snails and slugs.
  • Displace – force out native species. The invasive periwinkle uses its larger size to force out the native species.
  • Grazing – Eating plants right down to the surface from which they grow, baring or mowing areas. Perwinkles eat the algae down to bare rock consuming about 2 two-foot strips of algae as wide as their body each day.
  • Operculum – trap door or flap made of keratin (finger nail material), that flaps closed to protect the periwinkle’s soft body that is in its shell.

Fun Facts

  • Gastropods are one of a few groups of animals that have been successful in all three major habitats: the ocean, fresh waters, and land.
  • You can eat periwinkles, and they are as tasty as steamers but more work to get out of their shell and to remove their operculums.
  • The periwinkle’s foot is its belly.
  • Its shell grows in spirals as the periwinkle grows.

A fun activity to try!

  • Hum to a periwinkle. If you pick a periwinkle off a rock, hold it carefully while quietly humming to it, it may open its operculum (trap door) and poke its head out with its antennae and eyes so you can see more parts of its body.


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