Description of biotope or habitat type
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Ocnus planci aggregations on sheltered sublittoral muddy sediment
Physical habitat description
| Salinity | Full (30-35 ppt), Variable (18-35 ppt) |
|---|---|
| Wave exposure | Moderately exposed, Sheltered, Very sheltered, Extremely sheltered |
| Tidal streams | Weak (>1 kn), Very weak (negligible) |
| Substratum | Stones or shells on muddy sediment |
| Zone | Circalittoral, Infralittoral |
| Depth Band | 0-5 m, 5-10 m, 10-20 m, 20-30 m |
| Other Features |
Biotope origin
| Derived using data from | Video/Core |
| 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.
- 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.
Description
Dense aggregations of Ocnus planci on various substrata, typically muddy but occasionally with stones or shells, in sheltered conditions such as sea lochs. Philine aperta also characterises this biotope but is present in lower abundances than in SS.SMu.IFiMu.PhiVir. Other associated species vary but are typical of very sheltered muddy habitats and include the ophiuroids Ophiura spp. and Ophiothrix fragilis. Melanella alba, which parasitises holothurians, has been found in large numbers at one site.
Situation
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 |
|---|---|---|---|
| Ocnus lacteus | 27 | Frequent | 21-40% |
| Philine aperta | 20 | Frequent | 41-60% |
| Ocnus planci | 19 | Abundant | 41-60% |
| Asterias rubens | 7 | Occasional | 41-60% |
| Ophiura ophiura | 7 | Frequent | 21-40% |
| Liocarcinus depurator | 4 | Occasional | 21-40% |
| Ophiothrix fragilis | 4 | Frequent | 21-40% |
| Mya truncata | 3 | Occasional | 21-40% |
| Ophiocomina nigra | 3 | Occasional | 21-40% |
| Buccinum undatum | 2 | 21-40% | |
| Aequipecten opercularis | 1 | Rare | 21-40% |
| Alcyonium digitatum | 1 | Rare | 21-40% |
| Myxicola infundibulum | 1 | Rare | 21-40% |
| Ophiura albida | 1 | Rare | 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.IFiMu.Ocn | Ocnus planci aggregations on sheltered sublittoral muddy sediment |
| 2004 (04.05) | SS.SMu.IFiMu.Ocn | Ocnus planci aggregations on sheltered sublittoral muddy sediment |
| 1997 (97.06) | SS.IMU.MarMu.Ocn | Ocnus planci aggregations on sheltered sublittoral muddy sediment |
| 1996 (6.95) | SCR.Ocn |