EUNIS habitat classification 2017 > M - Marine benthic habitats > MC1 - Circalittoral rock > MC12 - Atlantic circalittoral rock > MC123 - Brachiopod and ascidian communities on Atlantic circalittoral rock > MC1231 - Solitary ascidians, including Ascidia mentula and Ciona intestinalis, on wave-sheltered Atlantic circalittoral rock > MC12311 - Solitary ascidians, including Ascidia mentula and Ciona intestinalis, with Antedon spp. on wave-sheltered Atlantic circalittoral rock

Solitary ascidians, including Ascidia mentula and Ciona intestinalis, with Antedon spp. on wave-sheltered Atlantic circalittoral rock

Quick facts

EUNIS habitat type code MC12311
Relation to Resolution 4 habitat type (used for designation of Emerald sites)

Description (English)

This variant occurs on circalittoral bedrock or boulder slopes in generally wave-sheltered conditions (often in sea lochs) with little tidal flow. It is frequently found on vertical or steeply-sloping rock. Apart from the large ascidians, Ascidia mentula and Ciona intestinalis, the rock surface usually has a rather sparse appearance. Scyphistomae larvae are often present on any vertical surfaces. Grazing by the sea urchin Echinus esculentus leaves only encrusting red algae (giving the bedrock/boulder substratum a pink appearance), cup corals Caryophyllia smithii and the keelworm Pomatoceros triqueter. There may be a few hydroid species present, such as Nemertesia spp. and Kirchenpaueria pinnata, occasional Alcyonium digitatum and occasional Metridium senile. Barnacles Balanus spp. and the colonial ascidian Clavelina lepadiformis also occasionally occur. At some sites, echinoderms such as the crinoid Antedon spp., the starfish Crossaster papposus and Asterias rubens and the brittlestar Ophiothrix fragilis (in low densities) may be found. The squat lobster Munida rugosa is likely to be found in crevices, under boulders, and the hermit crab Pagurus bernhardus may be observed moving around the rock surface. The brachiopod Neocrania anomala is frequently observed (especially where this biotope occurs shallower than unit MC1-234 for example). The saddle oyster Pododesmus patelliformis may occasionally be seen attached to the rock/boulder face.
Situation: This biotope is typical of one found in sheltered sealochs. On slightly more wave and tide exposed sites, a transition to the more diverse MC1-233 biotope will occur. Below MC1-2311, you may find the MC1-234 biotope (especially situated on the sills of sealochs).
Temporal variation: The abundance of C. intestinalis tends to fluctuate seasonally, so it may appear absent at a site at one time of year and then be present at other times, altering the visual appearance of the biotope. Other solitary ascidian species such as A. mentula and Ascidiella aspersa tend to be longer-lived (approximately 7 years and 3 years respectively).

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Invertebrates Alcyonium digitatum
Invertebrates Ascidia mentula
Invertebrates Ascidiella aspersa
Invertebrates Asterias rubens
Invertebrates Caryophyllia smithii
Invertebrates Ciona intestinalis
Invertebrates Crossaster papposus
Invertebrates Echinus esculentus
Invertebrates Kirchenpaueria pinnata
Invertebrates Metridium senile
Invertebrates Munida rugosa
Invertebrates Neocrania anomala
Invertebrates Ophiothrix fragilis
Invertebrates Pagurus bernhardus
Invertebrates Pododesmus patelliformis
Invertebrates Pomatoceros triqueter
Species scientific name English common name Species group
Alcyonium digitatum Invertebrates
Ascidia mentula Invertebrates
Ascidiella aspersa Invertebrates
Asterias rubens Invertebrates
Caryophyllia smithii Invertebrates
Ciona intestinalis Invertebrates
Crossaster papposus Invertebrates
Echinus esculentus Invertebrates
Kirchenpaueria pinnata Invertebrates
Metridium senile Invertebrates
Munida rugosa Invertebrates
Neocrania anomala Invertebrates
Ophiothrix fragilis Invertebrates
Pagurus bernhardus Invertebrates
Pododesmus patelliformis Invertebrates
Pomatoceros triqueter Invertebrates

Other classifications

History

Classification Code Habitat type name Relationship type Comment
EUNIS Habitat Classification 200410 A4.3111 Solitary ascidians, including Ascidia mentula and Ciona intestinalis, with Antedon spp. on wave-sheltered circalittoral rock same
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