BIOTIC Species Information for Neopentadactyla mixta
Researched byAngus Jackson Data supplied byMarLIN
Refereed byDr Andrew C. Campbell
Distribution and Habitat
Distribution in Britain & IrelandAll up the west coast of Scotland to Orkney and Shetland. A few isolated records from the east coast. Also from SW England, SW and NW Wales. In Ireland, particularly Kilkieran Bay, round the north and north-east, also the SE and SW corners.
Global distributionSouth, west and north coasts of the British Isles, the Faeroe Islands, the west coast of Norway (Molde) and the Atlantic coasts of France.
Biogeographic rangeNot researched Depth range15-70m
MigratorySee additional information   
Distribution Additional InformationAlthough not necessarily representative of all populations, Neopentadactyla mixta exhibits regular daily and seasonal movements within the substratum. In the Kilkieran Bay population, individuals withdraw further into the sediment between 1 or 4 hours after sunrise and remain in the substratum for 1 or 2 hours, re-emerging over a period of up to four hours. In September/October the entire population withdraws into the substratum and re-emerges in March/April. They remain buried in aerobic conditions at depths of up to 60 cm with tentacles retracted and not feeding. Considerable loss of condition occurs during this time. Direct absorption of dissolved organic matter may be important for nutrition. This state of torpor is not complete, respiration and activity is greatly reduced but some movement within the substratum still occurs. Depth of burial is maintained despite surface changes in gravel with water movement.

Substratum preferencesGravel / shingle
Physiographic preferencesOpen coast
Strait / sound
Ria / Voe
Biological zoneLower Infralittoral
Upper Circalittoral
Wave exposureExposed
Moderately Exposed
Very Sheltered
Tidal stream strength/Water flowModerately Strong (1-3 kn)
Weak (<1 kn)
SalinityFull (30-40 psu)
Habitat Preferences Additional Information
Distribution References Mortensen, 1927, Konnecker & Keegan, 1973, Keegan, 1974,
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