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Marine Habitat Classification

Description of biotope or habitat type

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   Very tide-swept faunal communities

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Extremely exposed, Very exposed, Exposed
Tidal streams Very strong (>6 kn), Strong (3-6 kn)
Substratum Bedrock, boulders
Zone Circalittoral - lower, Circalittoral - upper
Depth Band 10-20 m, 20-30 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.HCR.FaT Very tide-swept faunal 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 in wave-exposed, tide-swept narrows and straits on circalittoral bedrock and boulders. The biotopes within this complex are characterised by a high abundance of the robust hydroid Tubularia indivisa. The barnacle Balanus crenatus is characteristic of BalTub, the cushion sponges Halichondria panicea and Myxilla incrustans are characteristic of CTub.CuSp and Alcyonium digitatum is characteristic of CTub.Adig. The anemones Cylista elegans, Actinothoe sphyrodeta, Urticina felina, Corynactis viridis and Metridium senile are all found within this complex. Other species present in this high-energy complex are the sponges Amphilectus fucorum and Pachymatisma johnstonia, the bryozoans Alcyonidium diaphanum and Flustra foliacea, Cancer pagurus, Sertularia argentea and Asterias rubens. Within this complex, two biotopes have been identified: BalTub and CTub.


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
Tubularia indivisa 24 Abundant 81-100%
Balanus crenatus 11 Abundant 61-80%
Cylista elegans 9 Common 61-80%
Alcyonium digitatum 7 Frequent 61-80%
Alcyonidium diaphanum 3 Frequent 41-60%
Amphilectus fucorum 3 Frequent 41-60%
Urticina felina 3 Frequent 41-60%
Actinothoe sphyrodeta 2 Common 21-40%
Asterias rubens 2 Occasional 41-60%
Cancer pagurus 2 Occasional 41-60%
Corynactis viridis 2 Frequent 21-40%
Flustra foliacea 2 Frequent 21-40%
Halichondria panicea 2 Frequent 21-40%
Myxilla incrustans 2 Frequent 41-60%
Pachymatisma johnstonia 2 Occasional 41-60%
Sertularia argentea 2 Occasional 41-60%
Porifera 1 Frequent 21-40%
Metridium senile 1 Frequent 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) ECR.BS

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