Common Periwinkle

Fascinating facts about the Common Periwinkle

• The common periwinkle can survive at depths of up to 55 metres, extending its range far below the shoreline. It is primarily a resident of rocky shores in the higher and middle intertidal zones, where it clings to exposed surfaces. Occasionally it retreats into small tide pools, and it also inhabits muddy estuarine habitats, showing a remarkable ability to occupy both hard and soft substrates across a wide depth gradient.
• During its first two months, mortality can reach up to 94% per annum, falling to about 60% per annum for the remainder of the first year. Once they survive beyond fifteen months, annual mortality drops to roughly 23%.
• A single female periwinkle can lay between 10 000 and 100 000 eggs inside a hard corneous capsule that is released directly into the sea. The encapsulated embryos develop into pelagic larvae that remain in the water column for four to seven weeks before they settle to the bottom. Settlement of the young is most common from the end of May through June, after which the juveniles begin their benthic life on the shore.
• When a periwinkle encounters extreme cold or heat while climbing, it pulls back into its shell and begins to roll, a behaviour that can drop the snail back into the water and prevent desiccation. This rolling response is especially useful in the higher intertidal zone where the animal spends most of its time on exposed rock surfaces.
• The common periwinkle feeds mainly on algae, scraping the surface with its radula and also taking small invertebrates such as barnacle larvae when available. Its intense grazing removes large patches of algal cover, which in turn changes the texture of the habitat by turning soft-sediment areas into hard substrate.

Sources

Every fact above was checked against these pages, and kept only where one of them states it.

• Wikipedia

At a glance

About the Common Periwinkle

In the intertidal zone, where the tumultuous sea meets the unyielding shore, the Common Periwinkle makes its home, a tiny, tenacious pioneer that clings to the rocks with a steadfast determination. As the waves recede, it emerges, its shell a swirling vortex of brown and grey, as it begins its slow, deliberate journey in search of sustenance, leaving behind a trail of silvery threads that glisten like a whispered promise. With each gentle, probing motion, it navigates the intricate, wave-worn landscape, a small but resilient monarch of the shoreline realm.

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