Biodiversity & Conservation

Sea pens and burrowing megafauna in circalittoral soft mud



Image Mark Davies - Pennatula phosphorea and Turritella communis in muddy sediment. Image width ca XX cm.
Image copyright information

Distribution map

SS.SMu.CFiMu.SpnMeg 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

  • Pachycerianthus multiplicatus

Rare of scarce species associated with this biotope

Community Importance Species name Common Name
Important characterizing Virgularia mirabilis A sea pen
Key functional Callianassa subterranea Burrowing mud shrimp
Important functional Amphiura filiformis A brittlestar
Important functional Liocarcinus depurator Harbour crab


Sea pens characterise the biotope and the several sea pen species that are found within the biotope are represented by Virgularia mirabilis. Of the burrowing megafauna the burrowing crustaceans are probably the most important because they affect habitat complexity and bioturbation of the sediment and can influence the overall biotope species composition. The burrows of Callianassa subterranea, for example, allow a much larger surface area of sediment to become oxygenated, and thus enhance the survival of a considerable variety of small species (Pearson & Rosenberg, 1978). Brittle stars such as Amphiura filiformis can be present in large numbers. There are often scavengers in the biotope and although generally present in low numbers can be important to the biotope and are represented here by Liocarcinus depurator.

Additional information

This review can be cited as follows:

Hill, J.M. 2004. Sea pens and burrowing megafauna in circalittoral soft mud. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 27/11/2015]. Available from: <>