MB1-51β - Faciès à Vermetidés

Facies with Vermetids

Classification des habitats EUNIS 2022

Descriptif de l'habitat

Vermetids are sessile gastropods which develop near the middle level of the sea. These organisms, associated with the Neogoniolithon brassica-florida calcareous algae, build up organogenous formations in three shapes:
- The cornice or rim form: below the middle level of the sea on a subvertical rocky slope. In the north-western Mediterranean, these formations are covered with the Neogoniolithon brassica-florida and Lithophyllum byssoides calcareous algae.
- The atoll form: observed in the eastern Mediterranean (Israel and Crete), and in the Bermudas. These are rounded structures, depressed in the centre.
- The ‘pavement’ or ‘platform’ form: the standard structure described in Sicily is a horizontal corroded surface developed in the standing calcareous rock. The platform is pitted with shallow pools whose crests, as well as the outside edges (in the shape of pads or ledges) of the platform, are covered with Dendropoma cristatum Vermetids, often called Vermetus cristatus. In addition, the bottoms of the bowls of the platform can be colonised by Vermetus triquetrus, also known as Vermetus gregarius.
Although in the western Mediterranean the position of the platform is below the middle level of the sea and is located at the upper limit of the infralittoral stage, it is always mediolittoral in the eastern Mediterranean, where the platform develops at 0,2-0,3 meters above mid-wave level.

Bibliographie

European Topic Centre on Biological Diversity 2022. EUNIS marine habitat classification 2022 including crosswalks. Table Excel. (Source)