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Marine Habitat Classification

Description of biotope or habitat type

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   Amphiura filiformis and Ennucula tenuis in circalittoral and offshore sandy mud

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams Weak (>1 kn), Very weak (negligible)
Substratum Sandy mud
Zone Circalittoral
Depth Band 10-20 m, 20-30 m
Other Features

Biotope origin

Derived using data from Various
Faunal group Epifauna

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.SMu.CSaMu.AfilEten <I>Amphiura filiformis</I> and <I>Ennucula tenuis</I> in circalittoral and offshore sandy mud

  • 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.


In cohesive and non-cohesive sandy mud, off moderately exposed coasts in deep water dense populations of Amphiura filiformis with the bivalve Ennucula tenuis may occur. This biotope together with SS.SMu.CSaMu.AfilKurAnit, SS.SMu.CSaMu.ThyEten and SS.SSa.OSa.OfusAfil may be part of the Amphiura filiformis dominated infralittoral etage described by Glemarec (1973) and part of the 'off-shore muddy sand association' described by other workers (Jones 1951; Mackie 1990). Other species characteristic of this biotope may include the echinoderms Ophiura albida and Echinocardium flavescens and the bivalve Kurtiella bidentata. Phaxas pellucidus, Owenia fusiformis and Virgularia mirabilismay also be present. At the sediment surface the hydroid Sertularia argentea may be present although only at very low abundances. Variations of this biotope exist in the northern North Sea (SS.SMu.CSaMu.AfilKurAnit) and it is possible that more than one entity exists for this biotope. Collectively the biotopes SS.SMu.CSaMu.ThyEten, SS.SMu.CSaMu.AfilKurAnit, SS.SMu.CSaMu.AfilEten, SS.SMu.OMu.PjefThyAfil, and SS.SSa.OSa.OfusAfil, may form the Amphiura dominated components of the 'off-shore muddy sand association' described by other workers (Jones 1951; Thorson 1957; Mackie 1990) and the infralittoral etage described by Glemarec (1973).


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
Obelia longissima 57 Rare 81-100%
Sertularia argentea 26 Rare 61-80%
Amphiura filiformis 22 Super abundant 81-100%
Ennucula tenuis 15 Common 81-100%
Ophiura albida 12 Super abundant 81-100%
Echinocardium flavescens 10 Abundant 61-80%
Kurtiella bidentata 9 Common 61-80%
Cellaria fistulosa 8 Rare 41-60%
Hydrallmania falcata 8 Rare 41-60%
Owenia fusiformis 3 Common 41-60%
Phaxas pellucidus 3 Frequent 61-80%
Virgularia mirabilis 3 Abundant 41-60%
Abra nitida 2 41-60%
Antalis entalis 2 Frequent 41-60%
Cylichna cylindracea 2 Common 41-60%
Diplocirrus glaucus 2 61-80%
Lagis koreni 2 Common 41-60%
Ophelina acuminata 2 Common 41-60%
Scalibregma inflatum 2 41-60%

Similar biotopes or habitat types

SS.SMu.CSaMu.AfilEten may be distinguished from SS.SMu.CSaMu.AfilKurAnit by the abundance of the characterising species Ennucula tenuis in SS.SMu.CSaMu.AfilEten and by the importance of other characterising species such as Thysanocardia procera and Nephtys incise in SS.SMu.CSaMu.AfilKurAnit. SS.SMu.CSaMu.AfilEten is also generally found at greater depths and may be a deeper water extension of SS.SMu.CSaMu.AfilKurAnit.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SMu.CSaMu.AfilNten Amphiura filiformis and Nuculoma tenuis in circalittoral and offshore sandy mud
2004 (04.05) SS.SMu.CSaMu.AfilNten Amphiura filiformis and Nuculoma tenuis in circalittoral and offshore sandy mud
1997 (97.06) Part of SS.CMS.AfilEcor Amphiura filiformis and Echinocardium cordatum in circalittoral clean or slightly muddy sand

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