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Common Periwinkle

Littorina littorea

The common periwinkle is a robust and adaptable marine snail commonly found in intertidal zones along the North Atlantic coast. Its shell is thick and rounded, typically brown, gray, or black, with subtle growth lines. As it ages, the outer lip of its aperture thickens, providing additional protection. The periwinkle's strong foot allows it to cling tightly to rocks, reducing the risk of dislodgement by waves or predators. It feeds primarily on algae, scraping surfaces with its rasping radula, an organ lined with tiny, tooth-like structures. During low tide, it can seal itself inside its shell using a tough, plate-like operculum to prevent desiccation. The species reproduces by releasing fertilized eggs into the water, which develop into free-swimming larvae before settling into their adult form. Due to its resilience, the common periwinkle has successfully spread beyond its native range and is now found in various coastal habitats worldwide.

Fun Fact!

The common periwinkle was introduced to North America from Europe in the 1800s and has since become a dominant species in many intertidal ecosystems. Periwinkles can survive in both freshwater and saltwater for extended periods, allowing them to colonize new areas by traveling on floating debris.

Habitat & Range

Native to the northeastern Atlantic, from Europe to the Arctic, but now widespread along the North American coast from Labrador to North Carolina. Found in rocky intertidal zones, mudflats, and salt marshes.

Lifespan & Growth

Can live up to 10 years and grows to about 3-4 cm in shell length.

Role in Ecosystem

A key grazer in intertidal habitats, controlling algae growth and providing food for crabs, birds, and fish.

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