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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.

   Neopentadactyla mixta in circalittoral shell gravel or coarse sand

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Clean shell and stone gravel; very coarse sand with a finer sand fraction
Zone Infralittoral - lower, Circalittoral
Depth Band 10-20 m, 20-30 m, 30-50 m
Other Features

Biotope origin

Derived using data from Video/still
Faunal group Epifauna/Infauna

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.SCS.CCS.Nmix <I>Neopentadactyla mixta</I> in circalittoral shell gravel or coarse sand

  • 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.


Sublittoral plains of clean, shell, maerl and / or stone gravels or sometimes coarse sands, with frequent Neopentadactyla mixta. Pecten maximus may occur occasionally along with Lanice conchilega. Other epifaunal species may include Ophiura albida, Pagurus spp. and Callionymus spp. These sediments may be thrown into dunes by wave action or tidal streams. Widespread species such as Cerianthus lloydii and Chaetopterus variopedatus are present in many examples of this biotope. Scarcely recorded species such as Molgula oculata, Ophiopsila annulosa and Amphiura securigera may also be found. O. annulosa only occurs in records from the south-west of the British Isles. It should be noted that Neopentadactyla may exhibit periodicity in its projection out of, and retraction into, the sediment (Picton 1993). This biotope may be an epibiotic overlay of the biotope SS.SCS.CCS.MedLumVen.


This biotope may occur adjacent to maerl beds and to some extent in the lower infralittoral where some seaweeds may occur in low abundances.

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
Neopentadactyla mixta 50 Frequent 81-100%
Ophiura albida 8 Frequent 21-40%
Asterias rubens 5 Occasional 41-60%
Lanice conchilega 5 Occasional 21-40%
Pecten maximus 5 Occasional 41-60%
Callionymus lyra 3 Occasional 21-40%
Pagurus bernhardus 3 Occasional 21-40%
Cerianthus lloydii 2 Occasional 21-40%
Chaetopterus variopedatus 2 Occasional 21-40%
Nemertesia antennina 2 Occasional 21-40%
Adamsia palliata 1 Rare 21-40%
Callionymus reticulatus 1 Occasional 1-20%
Echinus esculentus 1 Occasional 21-40%

Similar biotopes or habitat types

SS.SCS.CCS.Nmix may occur in circalittoral dead maerl plains, often adjacent to maerl beds.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SCS.CCS.Nmix Neopentadactyla mixta in circalittoral shell gravel or coarse sand
2004 (04.05) SS.SCS.CCS.Nmix Neopentadactyla mixta in circalittoral shell gravel or coarse sand
1997 (97.06) SS.CGS.Ven.Neo Neopentadactyla mixta and venerid bivalves in circalittoral shell gravel or coarse sand
1996 (6.95) CGS.NeoBv

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