Skip to Content

Marine Habitat Classification

Description of biotope or habitat type

To understand more about what this page is describing, see How to use the classification. See also How to cite.

   Soft rock communities

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed
Tidal streams Moderately strong (1-3 kn)
Substratum Bedrock
Zone Circalittoral - upper
Depth Band 0-5 m, 5-10 m, 10-20 m
Other Features Soft rock

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.SfR Soft rock communities

  • 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 complex occurs on moderately wave-exposed, circalittoral soft bedrock subject to moderately strong tidal streams. As this complex is found in highly turbid water conditions, the circalittoral zone may begin at the low water mark, due to poor light penetration. This complex is dominated by the piddock Pholas dactylus. Other species typical of this complex include the polychaete Polydora and Bispira volutacornis, the sponges Cliona celata and Suberites ficus, the bryozoan Flustra foliacea, Alcyonium digitatum, the starfish Asterias rubens, the mussel Mytilus edulis and the crab Necora puber and Cancer pagurus. Foliose red algae may also be present. Three biotopes have been identified within this complex: Pid, Pol and Hia. Please note: in areas subject to very high turbidity, biotopes within this biotope complex may occur in the infralittoral and even the littoral zone.


No situation data available.

Temporal variation

No temporal variation data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Pholas dactylus 68 Common 61-80%
Polydora 4 Abundant 21-40%
Cliona celata 3 Occasional 21-40%
Foliose red algae 3 Occasional 21-40%
Alcyonium digitatum 2 Occasional 21-40%
Asterias rubens 2 Occasional 21-40%
Flustra foliacea 2 Occasional 21-40%
Mytilus edulis 2 Common 1-20%
Suberites ficus 2 Frequent 1-20%
Bispira volutacornis 1 Occasional 1-20%
Cancer pagurus 1 Occasional 21-40%
Necora puber 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code
1997 (97.06) CR.MCR.SfR

Back to top