EUNIS habitat classification 2012 amended 2019 > A - Marine habitats > A5 - Sublittoral sediment > A5.4 - Sublittoral mixed sediments > A5.44 - Circalittoral mixed sediments > A5.445 - Ophiothrix fragilis and/or Ophiocomina nigra brittlestar beds on sublittoral mixed sediment

Ophiothrix fragilis and/or Ophiocomina nigra brittlestar beds on sublittoral mixed sediment

English name: Ophiothrix fragilis and/or Ophiocomina nigra brittlestar beds on sublittoral mixed sediment

Quick facts

EUNIS habitat type code A5.445
Bern Convention Included in a Resolution 4 habitat type at a higher level (A5)

Description (English)

Circalittoral sediment dominated by brittlestars (hundreds or thousands m-2) forming dense beds, living epifaunally on boulder, gravel or sedimentary substrata. Ophiothrix fragilis and Ophiocomina nigra are the main bed-forming species, with rare examples formed by Ophiopholis aculeate. Brittlestar beds vary in size, with the largest extending over hundreds of square metres of sea floor and containing millions of individuals. They usually have a patchy internal structure, with localized concentrations of higher animal density. Ophiothrix fragilis or Ophiocomina nigra may dominate separately or there may be mixed populations of the two species. Ophiothrix beds may consist of large adults and tiny, newly-settled juveniles, with animals of intermediate size living in nearby rock habitats or among sessile epifauna. Unlike brittlestar beds on rock, the sediment based beds may contain a rich associated epifauna (Warner, 1971; Allain, 1974; Davoult & Gounin, 1995). Large suspension feeders such as the octocoral Alcyonium digitatum, the anemone Metridium senile and the hydroid Nemertesia antennina are present mainly on rock outcrops or boulders protruding above the brittlestar-covered substratum. The large anemone Urticina feline may be quite common. This species lives half-buried in the substratum but is not smothered by the brittlestars, usually being surrounded by a 'halo' of clear space (Brun, 1969; Warner, 1971). Large mobile animals commonly found on Ophiothrix beds include the starfish Asterias rubens, Crossaster papposus and Luidia ciliaris, the urchins Echinus esculentus and Psammechinus miliaris, edible crabs Cancer pagurus, swimming crabs Necora puber, Liocarcinus spp., and hermit crabs Pagurus bernhardus. The underlying sediments also contain a diverse infauna including the bivalve Abra alba. Warner (1971) found that numbers and biomass of sediment dwelling animals were not significantly reduced under dense brittlestar patches.

Source: EUNIS habitat classification

Vegetation types

Relation to vegetation types (syntaxa)

Not available

Species mentioned in habitat description

Invertebrates Abra alba
Invertebrates Alcyonium digitatum
Invertebrates Asterias rubens
Invertebrates Cancer pagurus
Invertebrates Crossaster papposus
Invertebrates Echinus esculentus
Invertebrates Luidia ciliaris
Invertebrates Metridium senile
Invertebrates Necora puber
Invertebrates Nemertesia antennina
Invertebrates Ophiocomina nigra
Invertebrates Ophiothrix fragilis
Invertebrates Pagurus bernhardus
Invertebrates Psammechinus miliaris
Species scientific name English common name Species group
Abra alba Invertebrates
Alcyonium digitatum Invertebrates
Asterias rubens Invertebrates
Cancer pagurus Invertebrates
Crossaster papposus Invertebrates
Echinus esculentus Invertebrates
Luidia ciliaris Invertebrates
Metridium senile Invertebrates
Necora puber Invertebrates
Nemertesia antennina Invertebrates
Ophiocomina nigra Invertebrates
Ophiothrix fragilis Invertebrates
Pagurus bernhardus Invertebrates
Psammechinus miliaris Invertebrates

Other classifications

Classification Code Habitat type name Relationship type
Marine Habitat Classification Britain/Ireland 0405 SS.SMx.CMx.OphMx <I>Ophiothrix fragilis</I> and/or <I>Ophiocomina nigra</I> brittlestar beds on sublittoral mixed sediment source
CORINE Land Cover 5.2.3. Sea and ocean n/a
For relation to plant communities (syntaxa), see Vegetation types

History

Classification Code Habitat type name Relationship type
MNCR BioMar 97.06 (Britain & Ireland) MCR.Bri.Oph Ophiothrix fragilis and/or Ophiocomina nigra beds on slightly tide-swept circalittoral rock or mixed substrata source
EUNIS Habitat Classification 200410 A5.445 Ophiothrix fragilis and/or Ophiocomina nigra brittlestar beds on sublittoral mixed sediment same
EUNIS Habitat Classification 200308 A4.445 Ophiothrix fragilis brittlestar beds with moderately strong tidal streams same
EUNIS Habitat Classification 200308 A3.651 Ophiothrix fragilis and/or Ophiocomina nigra beds on slightly tide-swept circalittoral rock or mixed substrata wider
EUNIS Habitat Classification 200202 A3.651 Ophiothrix fragilis and/or Ophiocomina nigra beds on slightly tide-swept circalittoral rock or mixed substrata same
EUNIS Habitat Classification 200202 A4.445 Ophiothrix fragilis brittlestar beds with moderately strong tidal streams same
EUNIS Habitat Classification 199910 A3.651 Ophiothrix fragilis and/or Ophiocomina nigra beds on slightly tide-swept circalittoral rock or mixed substrata same
European Environment Agency (EEA)
Kongens Nytorv 6
1050 Copenhagen K
Denmark
Phone: +45 3336 7100