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Marine Habitat Classification

Description of biotope or habitat type

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   Cylista undata and Ascidiella aspersa on infralittoral sandy mud

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Sheltered, Very sheltered
Tidal streams Moderately strong (1-3 kn)
Substratum Sandy mud
Zone Infralittoral
Depth Band 5-10 m, 10-20 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.ISaMu.CundAasp <I>Cylista undata</I> and <I>Ascidiella aspersa</I> on infralittoral 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.


Sheltered sublittoral mud or sandy mud in shallow water with relatively few conspicuous species may be characterised by the anemone Cylista undata in low numbers and the tunicate Ascidiella aspersa. Other taxa may include Carcinus maenas, Pagurus bernhardus and terebellid polychaetes. The burrowing anemones Cerianthus lloydii may also be found occasionally. The status of this biotope is uncertain at present as it is not known whether it is an impoverished, disturbed or epifaunal variant of other sheltered, shallow mud biotopes such as SS.SMu.IFiMu.PhiVir or if the areas in which it has been recorded have been incompletely surveyed.


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
Cylista undata 24 Occasional 61-80%
Carcinus maenas 18 Occasional 61-80%
Ascidiella aspersa 7 Frequent 41-60%
Pagurus bernhardus 6 Occasional 41-60%
Seraphsidae 4 Occasional 41-60%
Asterias rubens 3 Occasional 41-60%
Cerianthus lloydii 3 Occasional 21-40%
Hydractinia echinata 3 Occasional 21-40%
Liocarcinus depurator 3 Occasional 21-40%
Pomatoschistus 3 Occasional 21-40%
Metridium senile 2 Rare 21-40%
Myxicola infundibulum 2 Occasional 21-40%
Buccinum undatum 1 Rare 21-40%
Awaous commersoni 1 Occasional 21-40%
Pomatoschistus minutus 1 Occasional 21-40%

Similar biotopes or habitat types

Not applicable or unknown.

Classification history of this biotope or habitat type

Classification version Code Habitat name
2015 (15.03) SS.SMu.ISaMu.SundAasp Sagartiogeton undatus and Ascidiella aspersa on infralittoral sandy mud
2004 (04.05) SS.SMu.ISaMu.SundAasp Sagartiogeton undatus and Ascidiella aspersa on infralittoral sandy mud

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