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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.

   Infralittoral muddy sand

Physical habitat description

Salinity Full (30-35 ppt), Variable (18-35 ppt)
Wave exposure Moderately exposed, Sheltered
Tidal streams Moderately strong (1-3 kn), Weak (>1 kn), Very weak (negligible)
Substratum Fine to very fine sand with a silt fraction
Zone Infralittoral
Depth Band 0-5 m, 5-10 m, 10-20 m
Other Features

Biotope origin

Derived using data from Various
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.SSa.IMuSa Infralittoral muddy 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.


Non-cohesive muddy sand (with 5% to 20% silt/clay) in the infralittoral zone, extending from the extreme lower shore down to more stable circalittoral zone at about 15-20 m. The habitat supports a variety of animal-dominated communities, particularly polychaetes (Magelona mirabilis, Spiophanes bombyx and Chaetozone setosa), bivalves (Fabulina fibula and Chamelea gallina) and the urchin Echinocardium cordatum.


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
Echinocardium cordatum 22 Frequent 61-80%
Magelona mirabilis 16 Common 81-100%
Fabulina fabula 14 Common 81-100%
Lanice conchilega 14 Occasional 41-60%
Spiophanes bombyx 13 Common 61-80%
Arenicola marina 12 Frequent 41-60%
Chaetozone setosa 11 Common 81-100%
Pagurus bernhardus 11 Occasional 41-60%
Ensis 8 Frequent 41-60%
Nephtys 7 Common 61-80%
Asterias rubens 5 Occasional 41-60%
Chamelea gallina 5 Common 41-60%
Liocarcinus depurator 4 Occasional 21-40%
Diatoms - film 3 Common 21-40%
Nucula nitidosa 3 Frequent 41-60%
Pleuronectidae 2 Frequent 21-40%
Bathyporeia 2 Frequent 21-40%
Cirratulidae 2 Common 21-40%
Nephtys cirrosa 2 Common 21-40%
Nephtys hombergii 2 41-60%
Phaxas pellucidus 2 Common 21-40%
Abra alba 1 21-40%
Abra prismatica 1 21-40%
Diastylis bradyi 1 21-40%
Scoloplos armiger 1 21-40%
Spio 1 Frequent 21-40%
Pomatoschistus 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.SSa.IMuSa Infralittoral muddy sand
2004 (04.05) SS.SSa.IMuSa Infralittoral muddy sand
1997 (97.06) Part of SS.IMS.FaMS Shallow muddy sand faunal communities

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