Inachus dorsettensis

Researched By	Rose Edwards	Data Supplied By	MarLIN
Refereed by	This information is not refereed.
Taxonomy
Scientific name	Inachus dorsettensis	Common name	Scorpion spider crab
MCS Code	S1526	Recent Synonyms	None
Phylum	Crustacea	Subphylum
Superclass		Class	Eumalacostraca
Subclass	Eucarida	Order	Decapoda
Suborder	Pleocyemata	Family	Majidae
Genus	Inachus	Species	dorsettensis
Subspecies
Additional Information
Taxonomy References	Crothers & Crothers, 1988, Hayward & Ryland, 1995b, Ingle, 1997, Ingle, 1980, Howson & Picton, 1997, Ingle, 1996
General Biology
Growth form	Articulate	Feeding method	Omnivore, Scavenger, Predator
Mobility/Movement	Crawler	Environmental position	Epibenthic
Typical food types		Habit	Free living
Bioturbator		Flexibility	None (< 10 degrees)
Fragility	Fragile	Size	Small-medium(3-10cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	1km-10km	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
Additional Information	Inachus 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 & Ireland	Widely distributed around the British Isles with sparse records along the east coast of England and west coast of Ireland.
Global distribution	Norway to S. Africa and Med ( Hayward & Ryland, 1995).
Biogeographic range	Not researched	Depth range	To at least 300 m depth (Ingle, 1997).
Migratory	Insufficient information
Distribution Additional Information
Substratum preferences	Pebbles, Coarse clean sand, Fine clean sand, Sandy mud, Mud, Muddy sand	Physiographic preferences	Insufficient information
Biological zone	Insufficient information	Wave exposure	Insufficient information
Tidal stream strength/Water flow	Insufficient information	Salinity	Insufficient information
Habitat Additional Information	Inachus dorsettensis was found to be scarce on coarse substrata and most abundant on muddy sand near the Isle of Mann (Hartnoll et al., 1993).
AMBI Group (Borja et al., 2000)	I
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 type	Gonochoristic	Developmental mechanism	Planktotrophic
Reproductive Season	All year round	Reproductive Location	Insufficient information
Reproductive frequency	Annual episodic	Regeneration potential	No
Life span	Insufficient information	Age at reproductive maturity	Insufficient information
Generation time	Insufficient information	Fecundity	Up to 5000 eggs
Egg/propagule size	Insufficient information	Fertilization type
Larvae/Juveniles Larval/Juvenile dispersal potential >10km Larval settlement period Year round Duration of larval stage 1-2 months
Additional Information	Females 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