Neocrania anomala and Protanthea simplex on very wave-sheltered circalittoral rock

Description (English)

This variant typically occurs on deep, lower circalittoral bedrock or boulder slopes (often-vertical walls) in the landward, very sheltered basins of fjordic sealochs. In these very sheltered conditions, there are frequently dense populations of the anemone Protanthea simplex growing on the silty boulder or rock slope, and on the tubes of the parchment worm Chaetopterus variopedatus. The underlying rock surfaces are usually covered with encrusting red algae, the polychaete Pomatoceros triqueter, the brachiopod Neocrania anomala, the saddle oyster Pododesmus patelliformis and the conspicuous fan worm Sabella pavonina. Scattered colonies of Alcyonium digitatum are occasionally present along with the hydroid Bougainvillia ramosa. The barnacle Balanus balanus and the hermit crab Pagurus bernhardus is occasionally seen on boulder or rock surface, whilst underneath in crevices, the squat lobster Munida rugosa may be present. A diverse range of solitary ascidians, typically found in sheltered conditions, are often present including Ciona intestinalis, Corella parallelogramma, Polycarpa pomaria, Ascidia mentula and Ascidia virginea. Echinoderms such as brittlestars Ophiothrix fragilis are frequently seen with their arms protruding from crevices in the rock, whilst the starfish Asterias rubens, the sea urchin Echinus esculentus and Psammechinus miliaris are occasionally found on the boulder or rock surface. The whelk Buccinum undatum is often present but in very low numbers.
Situation: Where this biotope occurs on vertical rock cliffs, you tend to find silted sugar kelp Laminaria saccharina communities above A4.314, in the infralittoral zone (A3.313). Where A4.314 occurs on a rock or boulder slope and due to the very sheltered nature of the habitat, it is common to find a mud plain community where slope ends (A5.3). Species such as the seapen Funiculina quadrangularis, the anemone Cerianthus lloydii and the Norway lobster Nephrops norvegicus are typically abundant.

Source: EUNIS habitat classification