BIOTIC

BIOTIC Species Information for Musculus discors
All Taxonomy Biology Distribution Reproduction

Researched by	Lizzie Tyler	Data supplied by	University of Sheffield
Refereed by	This information is not refereed.
Distribution and Habitat
Distribution in Britain & Ireland	Common around most of the British Isles from Shetland to the Channel Isles.
Global distribution	A panartic bivalve, found from the Arctic Circle south through the Bering Sea to Japan or to the Puget Sound in the Pacific or south to New York or Madeira in the Atlantic, including the western Baltic and Mediterranean.
Biogeographic range	Not researched	Depth range
Migratory	Non-migratory / Resident
Distribution Additional Information	Musculus discors forms gregarious clumps on the holdfasts of seaweeds, especially Corallina officinalis, Fucus spp. Laminaria spp. and Desmarestia sp. On laminarians, Musculus discors may cover the holdfast and bottom part of the stipe (Jeffreys, 1863; Ockelmann, 1958; Tebble, 1976). Small specimens (<20mm) were reported nestled in interstices between barnacles and the old holdfasts of tunicates (MacGinitie, 1955). Merrill & Turner (1963) found Musculus discors fouling the upper surface of the sea scallop Placopecten magellanicus. Most records reported Musculus discors in the shallow subtidal to depths of up to 50m in the British Isles. However, it has been reported to be abundant above 30-40m in east Greenland, to form a well developed community at 60-100m in the Fosse de la Hague in the English Channel (Cabioch, 1968), to occur from 0 -374m in the Barents Sea (Ockelmann, 1958), and to be common in most trawls from 130-741 ft (ca 39-225m) at Point Barrow, Alaska (MacGinitie, 1955). Musculus discors occasionally forms dense aggregations, especially in strong tidal streams, covering rock surfaces, forming the biotope MCR.Mus.

Substratum preferences	Algae Bedrock Large to very large boulders Small boulders Gravel / shingle Mud	Physiographic preferences	Open coast Strait / sound Sealoch Ria / Voe Enclosed coast / Embayment
Biological zone	Lower Eulittoral Sublittoral Fringe Upper Infralittoral Lower Infralittoral Upper Circalittoral	Wave exposure	Exposed Moderately Exposed Sheltered Very Sheltered Extremely Sheltered
Tidal stream strength/Water flow	Strong (3-6 kn) Moderately Strong (1-3 kn) Weak (<1 kn)	Salinity	Variable (18-40 psu) Full (30-40 psu)
Habitat Preferences Additional Information
Distribution References	Thorson, 1935, Tebble, 1976, Fish & Fish, 1996, Baldock et al., 1998, Könnecker & Keegan, 1983, Ockelmann, 1958, Thorson, 1946, MacGinitie, 1955, Murray, E. et al., 1999, Thorpe, 1998, Könnecker, 1977, Cartlidge & Hiscock, 1980, Bruce et al., 1963, Seaward, 1990, Brazier et al., 1999,