Skip to Content

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.

   Verrucaria mucosa and/or Hildenbrandia rubra on upper to mid shore cave walls

Physical habitat description

Salinity Full (30-35 ppt)
Wave exposure Exposed, Moderately exposed
Tidal streams
Substratum Bedrock
Zone Eulittoral - mid, Eulittoral - upper, Littoral fringe
Depth Band
Other Features Moist, dark caves

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 LR.FLR.CvOv.VmucHil <I>Verrucaria mucosa</I> and/or <I>Hildenbrandia rubra</I> on upper to mid shore cave walls

  • 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'

Point data based on records in the UK Marine Recorder Snapshot.


The upper walls and ceilings of the entrances and inner reaches of upper shore caves affected by direct wave action (and therefore moistened by sea spray), characterised by a mosaic of the olive green lichen Verrucaria mucosa and the non-calcified encrusting red alga Hildenbrandia rubra. The black lichen Verrucaria maura and red coralline algae can be present, though not dominating. The fauna in these upper shore caves is generally limited, due to problems of desiccation. However, where conditions remain sufficiently moist, and particularly in crevices and fissures, the barnacle Semibalanus balanoides, the limpet Patella vulgata and winkles Littorina saxatilis may occur, particularly towards the rear of the cave. Although the characterising species of this biotope also occur on the shore, they do not generally occur in a distinct band other than in moist dark caves. The turf-forming red seaweed Rhodochorton purpureum may occasionally occur in low abundance (where A. purpurea covers an extensive area, generally on softer rock such as chalk, the biotope should be recorded as AudCla).


VmucHil generally occurs on upper walls and ceilings towards the rear of dark, moist caves, but can also occur at cave entrances that are directly affected by sea-spray. Where VmucHil occurs at cave entrances and to approximately 5 m into the cave, it is usually found above a zone of Sem and below GCv or AudCla. Further into the cave Sem is replaced completely by VmucHil. There are no records for VmucHil in soft rock caves.

Temporal variation


Characterising species

Taxon Relative importance of taxon for defining this community (%) Typical abundance - SACFOR scale % of core records where taxon was recorded
Verrucaria mucosa 38 Abundant 61-80%
Hildenbrandia rubra 30 Super abundant 61-80%
Patella vulgata 13 Common 61-80%
Verrucaria maura 8 Common 41-60%
Corallinaceae 2 Occasional 21-40%
Semibalanus balanoides 1 Occasional 21-40%
Rhodochorton purpureum 1 Frequent 21-40%
Littorina saxatilis 1 Occasional 21-40%

Similar biotopes or habitat types

Occurs in similar physical conditions, though mostly on vertical faces. The turf-forming red seaweed Audouinella spp. and C. caespitosa is more dense, while H. rubra is absent.

Back to top