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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.

   Tubularia indivisa on tide-swept circalittoral rock

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, boulder
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.CTub <I>Tubularia indivisa</I> on tide-swept 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 vertical and upper faces of strongly tide-swept, wave-exposed circalittoral bedrock and boulders. It is characterised by a dense carpet of the robust hydroid Tubularia indivisa. The barnacle Balanus crenatus, where present, is recorded as common. The accompanying species in the community are determined by tidal stream strength. On the more sheltered sides of headlands, where tidal streams are accelerated, sponges such as Pachymatisma johnstonia, Amphilectus fucorum, Myxilla incrustans and Halichondria panicea proliferate forming the CTub.CuSp sub-biotope. There may also be a scattered bryozoan turf, formed by criisid bryozoans. However, where tidal streams are slightly reduced, but on more wave-exposed coasts, anthozoans such as Alcyonium digitatum become more prominent forming the CTub.Adig biotope. Other species recorded in this biotope include the anemones Cylista elegans, Actinothoe sphyrodeta, Corynactis virdis and Urticina felina. There may be scattered clumps of hydroids such as Sertularia argentea and Nemertesia antennina. Where `relative shelter' is afforded by the topography of the seabed, the bryozoans Flustra foliacea, Alcyonidium diaphanum and the crab Cancer pagurus may be found. More ubiqutous species such as Asterias rubens and Calliostoma zizyphinum may also be present.


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%
Alcyonium digitatum 11 Frequent 81-100%
Cylista elegans 7 Common 61-80%
Balanus crenatus 6 Common 41-60%
Actinothoe sphyrodeta 4 Common 41-60%
Amphilectus fucorum 4 Frequent 41-60%
Pachymatisma johnstonia 4 Occasional 61-80%
Corynactis viridis 3 Frequent 41-60%
Alcyonidium diaphanum 2 Frequent 21-40%
Asterias rubens 2 Occasional 21-40%
Halichondria panicea 2 Frequent 21-40%
Myxilla incrustans 2 Frequent 41-60%
Nemertesia antennina 2 Frequent 21-40%
Urticina felina 2 Frequent 41-60%
Porifera 1 Frequent 21-40%
Calliostoma zizyphinum 1 Occasional 21-40%
Cancer pagurus 1 Rare 41-60%
Crisiidae 1 Common 21-40%
Flustra foliacea 1 Frequent 21-40%
Sertularia argentea 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.


CR.HCR.FAT.CTub Tubularia indivisa on tide-swept circalittoral rock, Devils Point, Plymouth. Rohan Holt© JNCC
CR.HCR.FAT.CTub Tubularia indivisa on tide-swept circalittoral rock, Devils Point, Plymouth. Rohan Holt© JNCC

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