BIOTIC Species Information for Inachus dorsettensis
Researched byRose Edwards Data supplied byMarLIN
Refereed byThis information is not refereed.
Scientific nameInachus dorsettensis Common nameScorpion spider crab
MCS CodeS1526 Recent SynonymsNone

PhylumCrustacea Subphylum
Superclass ClassEumalacostraca
SubclassEucarida OrderDecapoda
SuborderPleocyemata FamilyMajidae
GenusInachus Speciesdorsettensis

Additional Information
Taxonomy References Crothers & Crothers, 1988, Hayward & Ryland, 1995b, Ingle, 1997, Ingle, 1980, Howson & Picton, 1997, Ingle, 1996,
General Biology
Growth formArticulate
Feeding methodOmnivore
Environmental positionEpibenthic
Typical food types HabitFree living
Bioturbator FlexibilityNone (< 10 degrees)
FragilityFragile SizeSmall-medium(3-10cm)
HeightInsufficient information Growth RateInsufficient information
Adult dispersal potential1km-10km DependencyIndependent
General Biology Additional InformationInachus dorsettensis covers itself in tiny pieces of sponge and sea weed to provide camouflage. It is often found living in the tentacles of the snakelocks anemone (see Ingle, 1996 for further details). Max size post pubertal male and females were 35.5 mm and 29.5 mm off the Isle of Mann (Hartnoll et al., 1993).
Biology References Hartnoll et al., 1993,
Distribution and Habitat
Distribution in Britain & IrelandWidely distributed around the British Isles with sparse records along the east coast of England and west coast of Ireland.
Global distributionNorway to S. Africa and Med ( Hayward & Ryland, 1995).
Biogeographic rangeNot researched Depth rangeTo at least 300 m depth (Ingle, 1997).
MigratoryInsufficient information   
Distribution Additional Information

Substratum preferencesPebbles
Coarse clean sand
Fine clean sand
Sandy mud
Muddy sand
Physiographic preferencesInsufficient information
Biological zoneInsufficient information
Wave exposureInsufficient information
Tidal stream strength/Water flowInsufficient information
SalinityInsufficient information
Habitat Preferences Additional InformationInachus dorsettensis was found to be scarce on coarse substrata and most abundant on muddy sand near the Isle of Mann (Hartnoll et al., 1993).
Distribution References Crothers & Crothers, 1988, Hayward & Ryland, 1995b, Ingle, 1997, Ingle, 1980, JNCC, 1999, NBN, 2002, Ingle, 1996, Hartnoll et al., 1993,
Reproduction/Life History
Reproductive typeGonochoristic
Developmental mechanismPlanktotrophic
Reproductive SeasonAll year round Reproductive LocationInsufficient information
Reproductive frequencyAnnual episodic Regeneration potential No
Life spanInsufficient information Age at reproductive maturityInsufficient information
Generation timeInsufficient information FecundityUp to 5000 eggs
Egg/propagule sizeInsufficient information Fertilization type
Larval/Juvenile dispersal potential>10km Larval settlement periodYear round
Duration of larval stage1-2 months   
Reproduction Preferences Additional InformationFemales carry 3 egg batches per year (Fish & Fish, 1996) - as many as five per year have been reported in the Irish Sea (Bryant & Hartnoll, 1995). Only reproduce after terminal moult (Bryant & Hartnoll, 1995). Breeds all year round. In the lab, time taken for larvae to reach megalopae (the settling stage) approx 2-3 weeks and young crabs from planktonic megalopae took between 2 weeks to > one month (Lebour, 1927). Planktonic life 30 days in summer, longer at other times of year.
Reproduction References Fish & Fish, 1996, Bryant & Hartnoll, 1995, Lebour, 1927,
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