Common Periwinkle
ExploreInvertebrate
Common Periwinkle
littorina littorea
The Common Periwinkle (Littorina littorea) is a small but mighty marine gastropod that dominates the rocky shores of the North Atlantic. Known for its incredible resilience, this robust sea snail is a master of the intertidal zone, enduring pounding waves, fluctuating temperatures, and prolonged exposure to air during low tide. Native to Europe but now widespread along the North American coastline as an introduced species, it plays a massive role in shaping coastal ecosystems through its constant grazing on algae. Beyond its ecological significance, the Common Periwinkle has a long history intertwined with human culture. It has been gathered as a nutritious coastal food source for thousands of years, commonly boiled and eaten as a traditional seaside snack. Whether you are turning over rocks in a tidal pool or admiring the biodiversity of a rugged shoreline, you are almost guaranteed to cross paths with this hardy, ubiquitous little mollusk.
Habitat: Found along rocky coastlines, often clinging to rocks, tide pools, and seaweed in the intertidal zone.
Appearance
The Common Periwinkle features a thick, robust, spiral shell that typically measures between 1 to 3 centimeters in height. The shell has five to six slightly convex whorls, tapering to a sharply pointed apex. Its coloration is generally dark, ranging from grey-black to dark brown, though it can occasionally exhibit lighter spiral banding or a reddish tint. The opening of the shell is ovate with a pale inner lip. When active, its fleshy, dark-grey body and two sensory tentacles emerge. When threatened or exposed to air, the snail retreats and seals the opening with a dark, corneous 'trapdoor' known as an operculum.
KingdomAnimaliaPhylumMolluscaClassGastropodaOrderLittorinimorphaFamilyLittorinidaeGenusLittorina
Category
InvertebrateRarity
Common
Danger
1/5 · Very low
Snaps
Be the first to snap!
Interesting facts
Common Periwinkles were introduced to North America in the mid-19th century and have since become one of the most abundant shoreside snails there.
In the UK, eating boiled winkles using a pin to extract the snail from its shell is a traditional seaside activity dating back centuries.
Their constant grazing uses a radula covered in microscopic teeth that actually erodes coastal rocks over long periods of geological time.
To survive low tide on hot days, they can produce a specialized glue that attaches their shell lip to a rock, hanging freely to avoid absorbing excess heat from the stone.
Special abilities
Ability
Desiccation Resistance
It can seal its shell tightly with a horny trapdoor called an operculum, allowing it to survive for weeks out of water without drying out.
Ability
Radula Scraping
Equipped with a ribbon of microscopic, chitinous teeth known as a radula, it efficiently scrapes tough algae and diatoms directly off hard rock surfaces.
Ability
Wave Adhesion
It secretes a powerful mucus foot-hold that allows it to grip slick, wave-battered rocks, preventing it from being washed out to sea during storms.
Measurements & details
- Length
- 1-3 cm
- Weight
- 0.002-0.015 kg
- Lifespan
- 3-10 years
- Clutch Size
- 10000-100000
- Incubation
- 5-6 days
Diet & Feeding
The Common Periwinkle is primarily a grazing herbivore, feeding on microalgae and the germlings of larger seaweeds.
Age differences: Larvae are pelagic and feed on phytoplankton before settling on rocks to graze on benthic algae as adults.
Primary Foods
- Diatoms
- Microalgae
- Green algae
- Brown seaweed detritus
Foraging Method
- Grazing
Ecological connections
eaten by
European Green Crab
Carcinus maenas
A common predator that actively crushes and eats periwinkles.
eaten by
Herring Gull
Larus argentatus
Birds that forage in the intertidal zone will swallow periwinkles whole or drop them on hard rocks to break their shells.
host plant
Knotted Wrack
Ascophyllum nodosum
Provides a resting place and a source of epiphytic algae for the periwinkle to graze upon.
Traits
No trait badges are assigned for this object yet.
Also known as
No aliases listed yet.
Collections
Collections for this object will appear here as more themes are added.
Safety
Danger
1/5 · Very low
No special safety notes yet.
Frequently Asked Questions
How to identify Common Periwinkle?
The easiest way to identify Common Periwinkle is to use the Snappit nature identifier app.
How long is Common Periwinkle?
1-3 cm
How much does Common Periwinkle weigh?
0.002-0.015 kg
How long does Common Periwinkle live?
3-10 years
What does Common Periwinkle eat?
The Common Periwinkle is primarily a grazing herbivore, feeding on microalgae and the germlings of larger seaweeds.
Where is Common Periwinkle usually found?
Found along rocky coastlines, often clinging to rocks, tide pools, and seaweed in the intertidal zone.
How does Common Periwinkle hunt?
Grazing
How many eggs does Common Periwinkle lay?
10000-100000
Snap Map
Zoom in to split clusters and explore where this object has been snapped.
Loading map…
Recent Snaps
Recent snaps will appear here as new observations are added.
Where to spot
Park26 sightings12 species
Rhode Island, US
Bellevue Avenue Historic District
You might spot Rugosa Rose and American Herring Gull.
View guide →
Park30 sightings12 species
Rhode Island, US
Blithewold Mansion, Gardens and Arboretum
You might spot American Herring Gull and White-Tailed Deer.
View guide →
Park30 sightings12 species
US
Cape Arundel Summer Colony Historic District
You might spot Rugosa Rose and European Green Crab.
View guide →
Park30 sightings12 species
Massachusetts, US
Charter Street Historic District
You might spot Common Eastern Bumble Bee and Asian Lady Beetle.
View guide →
Park30 sightings12 species
Massachusetts, US
Chestnut Street District
You might spot Common Eastern Bumble Bee and Asian Lady Beetle.
View guide →
Park30 sightings12 species
Massachusetts, US
Downtown Salem District
You might spot Common Eastern Bumble Bee and Asian Lady Beetle.
View guide →
