Vermetid reefs (Dendropoma patraeum)

Vermetid platforms, or reefs, are built by the gastropod mollusc Dendropoma (Novastoa) petraeum, in association with some encrusting red seaweeds like Neogoniolithon brassica-florida. These reefs are often colonised by Vermetus triquetrus, another species of vermetid which, in both solitary and gregarious forms, occupies the portions of the structure that are permanently underwater. The bioconstructing vermetid is a highly gregarious species living in the tidal zone, to which it is particularly well adapted, thanks to the horny operculum that seals its shell opening in an airtight manner, thus enabling the animal to tolerate periodic emersions between tides. Vermetid reefs colonise the tidal zone exclusively on rocky coasts, with smaller formations according to the type of rock: calcarenite, limestone, dolomite, basalt and flysch. The presence of an abrasion platform thus becomes the essential condition for the formation of a reef. A second factor limiting the distribution and size of structures on a small scale is the extent of superficial hydrodynamics, as developed reefs are unlikely to be found in sheltered environments with calm waters

Código Eunis 2021: MA2551