Maja squinado

Researched By	Emily Wilson	Data Supplied By	MarLIN
Refereed by	This information is not refereed.
Taxonomy
Scientific name	Maja squinado	Common name	Common spider crab
MCS Code	S1515	Recent Synonyms	None
Phylum	Crustacea	Subphylum
Superclass		Class	Eumalacostraca
Subclass	Eucarida	Order	Decapoda
Suborder	Pleocyemata	Family	Majidae
Genus	Maja	Species	squinado
Subspecies
Additional Information
Taxonomy References	Howson & Picton, 1997, Hayward & Ryland, 1995b, Hayward et al., 1996, Ingle, 1980
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	Medium(11-20 cm)
Height	Insufficient information	Growth Rate	Insufficient information
Adult dispersal potential	>10km	Dependency	Independent
Sociability	Solitary
Toxic/Poisonous?	No
Additional Information	Up to 22.5 cm carapace length (Ingle, 1997). Although solitary, forms aggregated 'mounds' of individuals in late summer / autumn (Fish & Fish, 1996).
Biology References	Fish & Fish, 1996, Ingle, 1997
Distribution and Habitat
Distribution in Britain & Ireland	West and south-west coasts of Britain. It is at its northern limit in the UK.
Global distribution	NE Atlantic from Ireland to Guinea (W Africa) and Med to 150 m (Ingle, 1997).
Biogeographic range	Not researched	Depth range	Down to ca 75 m.
Migratory	Insufficient information
Distribution Additional Information
Substratum preferences	Bedrock, Coarse clean sand, Fine clean 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	Found on rocky sandy bottoms. Usually inhabits weed covered substrata or sandy / shingly substrata where weeds occur (Ingle, 1997).
Distribution References	Hayward & Ryland, 1995b, Hayward et al., 1996, NBN, 2002, JNCC, 1999, Picton & Costello, 1998, Hardy & Guiry, 2003, Morton, 1994, Ingle, 1997
Reproduction/Life History
Reproductive type	Gonochoristic	Developmental mechanism	Planktotrophic
Reproductive Season	Summer - Autumn	Reproductive Location	As adult
Reproductive frequency	Annual protracted	Regeneration potential	No
Life span	Insufficient information	Age at reproductive maturity	1-2 years
Generation time	Insufficient information	Fecundity	156,000 (Hartnoll, 1963)
Egg/propagule size	Insufficient information	Fertilization type	Internal
Larvae/Juveniles Larval/Juvenile dispersal potential 1km-10km Larval settlement period Insufficient information Duration of larval stage 2-10 days
Additional Information	Maturity 2 years in the Med (Hines et al., 1995). Main breeding season in south-west England between July - September (Lebour, 1927) and March - Sept in Ireland (Rodhouse, 1984). NE Atlantic in general, females bear eggs between March and October (Ingle, 1997). Time taken to reach the megalopa stage was reported to take ca 1 week in the laboratory (Lebour, 1927). In the Ría de Arousa, Spain, Maja squinado were reported to have moved up to 10.7 km within one month (González-Gurriarán & Freire, 1994). González-Gurriarán et al., (1993) estimated females to produce at least three consecutive broods during the yearly cycle. This is possible due to the storage of sperm which allows consecutive broods without the need for copulation before spawning (González-Gurriarán et al., 1996). In the UK and Ireland, only one brood is produced per yearly cycle (Rodhouse, 1984). In this species, the crabs do not moult again after becoming sexually mature i.e. the terminal moult is the pubertal moult.
Reproduction References	González-Gurriarán & Freire, 1994, González-Gurriarán et al, 1996, Rodhouse, 1984, Lebour, 1927, Ingle, 1997, Hartnoll, 1963