Biodiversity & Conservation

Musculus discors beds on moderately exposed circalittoral rock


<i>%Musculus discors% </i>beds on moderately exposed circalittoral rock
Distribution map

CR.MCR.M.Mus recorded (dark blue bullet) and expected (light blue bullet) distribution in Britain and Ireland (see below)

  • EC_Habitats

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

  • Musculus discors
  • Polymastia boletiformis
  • Stelligera stuposa
  • Hemimycale columella
  • Nemertesia antennina
  • Henricia oculata
  • Clavelina lepadiformis
Community Importance Species name Common Name
Important characterizing Musculus discors Green crenella


Musculus discors is the dominant space occupying species within this biotope, which may smother other species. Therefore, it has been considered to be 'important characterizing' in this review. The other species in the community are widespread and characteristic of the open coast, in which the Musculus discors beds are found. Therefore, the associated species vary with location and have little significant association with the Musculus discors bed itself. Therefore, reference has been made to Nemertesia ramosa to represent hydroids, Pentapora fascialis to represent bryozoans and Clavelina lepadiformis to represent ascidians and Urticina felina and Alcyonium digitatum to represent anthozoans occurring within the biotope.

Additional information

The epifauna may be exceptionally rich (Könnecker, 1977; Könnecker & Keegan, 1983). The MNCR recorded 323 species within this biotope, although not all species were present in all records of the biotope. Dominant species were detailed in other surveys by Cabioch (1968), Baldock et al. (1998) and JNCC (1999).

This review can be cited as follows:

Tyler-Walters, H. 2002. Musculus discors beds on moderately exposed circalittoral rock. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 01/12/2015]. Available from: <>