Description: A spider crab, with a strongly vaulted, ovoid carapace, its greatest width behind the middle; covered in numerous tubercles and spines. The front ends in two strong teeth which project beyond the outline of the carapace; lateral margins have 5 large and some small spinous teeth. The pincers are smooth, without spines; four pairs of walking legs of similar shape, but decreasing in size from front to back, covered in hairs but without spines. Juveniles often covered in algae or mud and adults often bearing epibiont organisms.
Global Distribution: Northeast Atlantic coasts from southern England and Ireland to Senegal, including the Azores, Madeira and Canary Islands.
BIOLOGICAL FEATURES
Size: Maximum length 22.0 cm. Maximum carapace width 18.0 cm.
Age: They can live more than 3 years, but the maximum age is not known.
Weight length rel.:
Growth type:
von Bertallanfy growth parameters:
Reproduction: Males and females migrate to deeper waters to mate. Mating takes place during migration and in deeper waters. Females spawn two or three times during their annual reproductive cycle. They are able to mate while their gonads are still in the early stages of development and store the sperm in spermathecae. Females are polyandric (mate with several males). Functionally mature but small males may be excluded from reproduction by larger males or female rejection.
Maturity: Based on morphometric maturity: males 136.5 mm, females 130.3 mm. Based on the median size of the adult population: males 141.1 mm, females 148.8 mm.
Behavioural ecology: Juveniles actively camouflage themselves with algae, which constitutes a protection mechanism to ward off predators. Adults tend to be covered with epibiont organisms and don't practice active camouflage anymore.
Population structure & migrations: Following morphological (Neumann 1998) and molecular (Sotelo et a. 2008) studies, the Northeastern Atlantic population formerly belonging to the species Maja squinado has been redescribed as a new species, Maja brachydactyla .
Genetic studies (mitochondrial DNA and microsatellites) reveal appreciable levels of genetic diversity within its distribution range.
Mating-related migration to deeper waters occurs in autumn.
ECOLOGICAL FEATURES
Depth range: SeaLifeBase 0 - 75 m
Habitat: Demersal. Occurs from the sublittoral area to depths of about 75 m, on rocky bottoms with algae.
Feeding habits: Feeds on seaweeds, molluscs, echinoderms, and ascidians. Prey items are mostly related to availability and feeding habits do not change much from juveniles to adults.
Trophic level:
FISHERIES
Commercial interest: Valuable commercial species. Captured (occasionally) with traps.
Conservation status: Not evaluated.
Nutritional information & food safety:
Proximate composition per 100 g:
energy value 128.1 kcal (6.4% DRV)
protein 16.7 g (33.5% DRV)
fat 3.6 g (5.1% DRV)
of which saturates 1.386 g (6.9% DRV)
omega-3 (EPA+DHA): 0.152 g (recommended: 0.250 - 2.0 g daily)
REFERENCES
Bernárdez C., Freire J., González-Gurriarán E. (2000). Feeding of the spider crab Maja squinado in rocky subtidal areas of the RÃa de Arousa (north-west Spain). Journal of the Marine Biological Association of the UK, 80(1): 95-102.
Corgos A., Freire J. 2006. Morphometric and gonad maturity in the spider crab Maja brachydactyla: a comparison of methods for estimating size at maturity in species with determinate growth. ICES Journal of Marine Science, 63: 851-859.
Corgos A., Verisimo P., Freire J. (2006). Timing and seasonality of the terminal molt and mating migration in the spider crab, Maja brachydactyla: evidence of alternative mating strategies. Journal of Shellfish Research, 25(2): 577-587.
Fischer W., Bianchi G., Scott W.B., eds. (1981). FAO species identification sheets for fishery purposes. Eastern Central Atlantic; fishing areas 34, 47 (in part). Canada Funds-in-Trust. Ottawa, Department of Fisheries and Oceans Canada, by arrangement with the Food and Agriculture Organization of the United Nations, vol. 6, 304 pp.
Flórez, L. G., & Rueda, P. F. (2003). Parámetros biológicos del centollo, Maja brachydactyla (Bachyura: Majidae), procedente de capturas comerciales en la zona central de Asturias (España) y su aplicación a la gestión pesquera. Naturalia Cantabricae, 2: 45-52.
IUCN (2014). The IUCN Red List of Threatened Species. Version 2014.1. www.iucnredlist.org
Marques A., Teixeira B., Barrento S., Anacleto P., Carvalho M.L., Nunes M.L. (2010). Chemical composition of Atlantic spider crab Maja brachydactyla: Human health implications. Journal of food composition and analysis, 23(3): 230-237.
Neumann V. (1998) A review of the Maja squinado (Crustacea: Decapoda: Brachyura) species-complex with a key to the eastern Atlantic and Mediterranean species of the genus. Journal of Natural History, 32(10-11): 1667-1684 .
Parapar J., Fernandez L., Gonzalez-Gurriaran E., Muino R. (1997). Epibiosis and masking material in the spider crab Maja squinado (Decapoda: Majidae) in the Ria de Arousa (Galicia, NW Spain). Cahiers de biologie marine, 38(4): 221-234.
Rotllant G., González-Gurriarán E., Fernández L., Benhalima K., Ribes E. (2007). Ovarian maturation of the multi-spawning spider crab Maja brachydactyla (Decapoda: Majidae) with special reference to yolk formation. Marine Biology, 152(2): 383-394.
Sotelo G., Morán P., Posada D. (2008). Genetic identification of the northeastern Atlantic spiny spider crab as Maja brachydactyla Balss, 1922. Journal of Crustacean Biology, 28(1): 76-81.
