Eroded periwinkle

Did you know?

During dry periods, the periwinkle draws into their shell and closes their operculum, also called a trap door. this keeps their gills moist, and also keeps fresh water and dry winds out. A periwinkle secretes a mucous glue that holds their shell to their rocky home. Adult eroded periwinkles can survive in this mode for extended dry periods for up to 17 weeks.

Conservation

The hobby or business of collecting seashells, especially by killing live animals in their shells, causes problems for marine creatures and could seriously affect the population of some snail species. Even empty shells have a place in the marine environment since many shells provide homes for other animals, like hermit crabs. Instead of collecting snails, it's best to look and not touch. You can photograph snails or make notes of their behavior and habits without disturbing them. Consider sending your observations to a marine biologist—you just might discover a never-before-seen behavior!

Cool facts

• Periwinkles can survive in fresh water, like puddles made by rain, for several days. Most marine animals can't do the same!
• Like most molluscs, a periwinkle uses a radula (a rough tongue or band of teeth) to scrape diatoms and algae from rocks. The rasping activity of the periwinkle may deepen high tide pools by almost one-half inch (1.25 cm) every 16 years. When a periwinkle population is thriving, they can considerably erode tide pools.
• The checkered periwinkle, L. scutula, ranges from Alaska to Baja California. This species lives lower down on the rocks than L. planaxis and is not as well adapted for dry periods. Instead, the checkered periwinkle migrates up and down rocks, following the high and low tides.