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.
Image copyright information

  • #
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

Text page icon Habitat description

Map icon Distribution of biotope in Britain and Ireland Scattered records from Fair Isle, Orkney; the rivers Teign and Dart, Devon; Lundy; the Bishops & Clerks, Skomer and off Dinas Head in Pembrokeshire; Cardigan Bay, Lleyn Peninsula, Bardsey and Menai Straits north Wales; Donlus Bay, south west Ireland; Tiree and Loch Roag, Isle of Lewis in west Scotland and St Kilda.
National importance Not available

Text page icon Description of biotope

For a full description of this biotope including characterizing species, distribution, survey information and references visit JNCC

Cobbles and pebbles with Balanus crenatus, Pomatoceros and a few bryozoan and coralline algal crusts are often found at the base of exposed cliff faces where scour action prevents colonization by more delicate species. Occasionally in tide-swept conditions tufts of hydroids such as Sertularia argentea and Hydrallmania falcata are present. This biotope often grades into MCR.Flu.SerHyd which is characterized by large amounts of the above hydroids on stones also covered in Pomatoceros and barnacles. The main difference here is that MCR.Flu.SerHyd seems to develop on more stable, consolidated cobbles and pebbles in moderate tides - these stones may be disturbed in the winter and therefore long-lived species are not found. (Information taken from the Marine Biotope Classification for Britain and Ireland, Version 97.06: Connor et al., 1997a, b).

Additional information icon Additional information

None entered.

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 26/11/2015]. Available from: <>