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Marine Habitat Classification

Description of biotope or habitat type

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   Caryophyllia smithii and Swiftia pallida on circalittoral rock

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Extremely exposed, Very exposed, Exposed, Moderately exposed, Sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Bedrock, boulders
Zone Circalittoral
Depth Band 10-20 m, 20-30 m, 30-50 m
Other Features

Download comparative physical and biological data. The comparative tables enable a rapid comparison of the species composition and principal physical characteristics between a given set of biotopes.

Distribution of habitat CR.MCR.EcCr.CarSwi <I>Caryophyllia smithii</I> and <I>Swiftia pallida</I> on circalittoral rock

  • Records used to define the biotope (core records)
  • Other records assigned to this biotope, marked as 'certain'
  • Other records assigned to this biotope, marked as 'uncertain'
  • Predicted extent of the level 3 (for sublittoral rock & deep sea) or 4 (for sublittoral sediment) habitat

Point data based on records in the UK Marine Recorder Snapshot. Predicted habitat extent is from UKSeaMap.


This biotope is typically found on the upper and vertical faces of very exposed through to wave-sheltered circalittoral bedrock and boulders, which are typically subject to weak tidal streams. It is characterised by dense aggregations of the cup coral Caryophyllia smithii and the sea fan Swiftia pallida on the silty substratum. Under the silt, bryozoan crusts such as Parasmittina trispinosa and encrusting red algae may be seen. This biotope may have a grazed appearance, perhaps attributable to the frequently occurring Echinus esculentus. There may be a sparse hydroid turf present, with species such as Nemertesia antennina, Nemertesia ramosa and Halecium halecinum present. The soft corals Alcyonium glomeratum and Alcyonium digitatum may be present on the tops of boulders along with the crinoids Antedon petasus and Antedon bifida. Other echinoderms occasionally observed include the starfish Marthasterias glacialis, Asterias rubens and Luidia ciliaris. Sponges feature only occasionally in this biotope, including species such as Cliona celata. The bryozoan Porella compressa may also be recorded. Ascidians occasionally present include Ascidia mentula, Clavelina lepadiformis and Ciona intestinalis. Under-boulder fauna typically consists of the crustacean Munida rugosa. The polychaete Spirobranchus triqueter may be seen encrusting the rocky surface. Two variants of this biotope have been identified; CarSwi.Aglo and CarSwi.LgAs. CarSwi.Aglo is a heavily silted biotope characterised by the sea fan S. pallida, the cup coral C. smithii and the soft coral A. glomeratum and is only present in Irish waters. CarSwi.LgAs has been recorded off the west coast of Scotland, and is characterised by large solitary ascidians and the cup coral C. smithii.


No situation data available.

Temporal variation

Not known.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Caryophyllia smithii 22 Common 81-100%
Swiftia pallida 14 Frequent 81-100%
Echinus esculentus 6 Frequent 61-80%
Parasmittina trispinosa 5 Occasional 61-80%
Corallinaceae 4 Abundant 41-60%
Nemertesia antennina 4 Occasional 61-80%
Ascidia mentula 3 Occasional 41-60%
Marthasterias glacialis 3 Occasional 41-60%
Antedon bifida 2 Occasional 41-60%
Asterias rubens 2 Occasional 41-60%
Cliona celata 2 Occasional 41-60%
Luidia ciliaris 2 Occasional 41-60%
Munida rugosa 2 Occasional 41-60%
Nemertesia ramosa 2 Occasional 21-40%
Alcyonium digitatum 1 Occasional 41-60%
Antedon petasus 1 Frequent 21-40%
Ciona intestinalis 1 Occasional 21-40%
Clavelina lepadiformis 1 Occasional 21-40%
Halecium halecinum 1 Occasional 21-40%
Spirobranchus triqueter 1 Occasional 21-40%
Porella compressa 1 Rare 41-60%
Alcyonium glomeratum 1 Frequent 21-40%

Similar biotopes or habitat types

see variant for details

see variant for details

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