BIOTIC

BIOTIC Species Information for Halidrys siliquosa
All Taxonomy Biology Distribution Reproduction

Researched by	Dr Harvey Tyler-Walters & Paolo Pizzolla	Data supplied by	MarLIN
Refereed by	Dr Stefan Kraan
Distribution and Habitat
Distribution in Britain & Ireland	Widely distributed and fairly common in the Britain and Ireland.
Global distribution	Restricted to the north east Atlantic, and recorded from northern Norway, Scandinavia, the Baltic Sea, Helgoland and the Netherlands south to the Bay of Biscay, north Portugal and the Canary Islands (John et al., 2004).
Biogeographic range	Not researched	Depth range	Intertidal to 4 m
Migratory	Non-migratory / Resident
Distribution Additional Information	On wave sheltered shores Halidrys siliquosa occur in the sublittoral and rock pools at low water. However, on wave exposed sites Halidrys siliquosa may also be found in deep high shore rock pools sheltered from the sun (Moss & Lacey, 1963). It is in such rock pools where the very weak water flow rate is likely to occur.

Substratum preferences	Bedrock Large to very large boulders Small boulders Rockpools Cobbles	Physiographic preferences	Open coast Strait / sound Sealoch Ria / Voe Enclosed coast / Embayment
Biological zone	Mid Eulittoral Lower Eulittoral Sublittoral Fringe Upper Infralittoral	Wave exposure	Exposed Moderately Exposed Sheltered Very Sheltered
Tidal stream strength/Water flow	Moderately Strong (1-3 kn) Weak (<1 kn) Very Weak (negligible)	Salinity	Full (30-40 psu) Variable (18-40 psu)
Habitat Preferences Additional Information
Distribution References	Fish & Fish, 1996, Dickinson, 1963, Norton, 1985, Hayward et al., 1996, Gibson et al., 2001, Lüning, 1990, JNCC, 1999, Picton & Costello, 1998, Lewis, 1964, Lüning, 1990, Guiry & Nic Dhonncha, 2002, Hardy & Guiry, 2003, Guiry & Nic Dhonncha, 2002, John et al., 2004,