Biodiversity & Conservation

Pomatoceros triqueter, Balanus crenatus and bryozoan crusts on mobile circalittoral cobbles and pebbles



Image Jon Davies - Cobbles with dense Pomatoceros species (ECR.PomByC). Image width ca 50 cm.
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Distribution map

SS.SCS.CCS.PomB recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats
  • UK_BAP

For a list of 2004 characterising species please see the JNCC website.

Species indicative of sensitivity

To assess the sensitivity of the biotope, the sensitivity of component species is reviewed. Those species that are considered to be particularly indicative of the sensitivity of the biotope, and for which research has been undertaken in detail are shown below (see selection criteria). The biology of other component species of the biotope is also taken into account wherever information is known to the researcher.

Species found especially in this biotope

  • Pomatoceros triqueter
  • Balanus crenatus
Community Importance Species name Common Name
Important characterizing Pomatoceros triqueter A tubeworm
Important characterizing Balanus crenatus An acorn barnacle


The dominant characterizing species are Pomatoceros triqueter and Balanus crenatus which if lost would result in loss of the biotope as described. Reference was made to Electra pilosa to represent the sensitivity of encrusting bryozoans and to Nemertesia ramosa and Cordylophora caspia to represent the erect hydroids.

Additional information

The MNCR recorded 265 species in 9 records of this biotope. But only a few dominant species occurred in any abundance and most species were only occasional or rare, and not all species occurred in all records of the biotope.

This review can be cited as follows:

Tyler-Walters, H. 2002. Pomatoceros triqueter, Balanus crenatus and bryozoan crusts on mobile circalittoral cobbles and pebbles. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 25/11/2015]. Available from: <>