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Marine Habitat Classification

Description of biotope or habitat type

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   Sertularia cupressina and Hydrallmania falcata on tide-swept sublittoral sand with cobbles or pebbles.

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams Strong (3-6 kn), Moderately strong (1-3 kn), Weak (>1 kn)
Substratum Medium to fine sand with pebbles and cobbles
Zone Circalittoral, Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 m
Other Features Sand scour

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 SS.SSa.IFiSa.ScupHyd <I>Sertularia cupressina</I> and <I>Hydrallmania falcata</I> on tide-swept sublittoral sand with cobbles or pebbles.

  • 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.


Shallow sands with cobbles and pebbles, exposed to strong tidal streams, with conspicuous colonies of hydroids, particularly Hydrallmania falcata and to a lesser extent Sertularia cupressina and S. argentea. These hydroids are tolerant to periodic submergence and scour by sand. Both diving and dredge surveys will easily record this biotope. Flustra foliacea, Balanus crenatus and Alcyonidium diaphanum may also occur on the more stable cobbles and pebbles, with Urticina felina and occasional Lanice conchilega present in the sand. Infaunal components of the other biotopes in the SSA or SCS complex may occur in this biotope as may elements of the 'Venus' associations; indeed, this biotope may be at one extreme of the spectrum of such associations (E.I.S. Rees pers. comm. 1997) and this biotope may be best considered an epibiotic overlay.


No situation data available.

Temporal variation

No temporal data available.

Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Hydrallmania falcata 18 Occasional 61-80 %
Sertularia argentea 3 Occasional 21-40 %
Sertularia cupressina 12 41-60 %
Urticina felina 8 Rare 41-60 %
Lanice conchilega 11 Occasional 61-80 %
Sabella pavonina 1 Rare 21-40 %
Balanus crenatus 4 Rare 41-60 %
Pagurus bernhardus 12 Rare 61-80 %
Liocarcinus depurator 1 Rare 21-40 %
Carcinus maenas 5 41-60 %
Mytilus edulis 1 21-40 %
Alcyonidium diaphanum 6 Occasional 41-60 %
Flustra foliacea 2 Rare 21-40 %
Asterias rubens 5 Occasional 41-60 %

Similar biotopes or habitat types

The less scoured biotope FluHyd occurs in deeper water where there is less sand and a higher proportion of stones and cobbles.

Classification history of this biotope or habitat type

Classification version Code
96.7 IGS.Scup

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