BIOTIC Species Information for Carcinus maenas
|Researched by||Ken Neal & Paolo Pizzolla||Data supplied by||MarLIN|
|Refereed by||This information is not refereed.|
|Scientific name||Carcinus maenas||Common name||Common shore crab|
|MCS Code||S1594||Recent Synonyms||None|
|Additional Information||No text entered|
|Taxonomy References||Hayward et al., 1996, Hayward & Ryland, 1995b, Fish & Fish, 1996, Howson & Picton, 1997,|
|Typical food types||Any animal or plant material (see additional information).||Habit||Free living|
|Bioturbator||Flexibility||None (< 10 degrees)|
|Height||Insufficient information||Growth Rate||See additional information|
|Adult dispersal potential||1km-10km||Dependency||Independent|
|General Biology Additional Information||General
Carcinus maenas is an easily identifiable crab of estuaries, sheltered rocky shores and offshore waters (Crothers, 1968). With increasing exposure on rocky shores, Carcinus maenas is replaced by other crab species such as the velvet swimming crab Necora puber, the bristly crab Pilumnus hirtellus, the edible crab Cancer pagurus and Montagu's crab Xantho incisus, and on increasingly exposed sandy areas by Pennant's swimming crab Portumnus latipes, the masked crab Corystes cassivelaunus, the harbour crab Liocarcinus depurator and the flying crab, Liocarcinus holsatus (Crothers, 1968).
Some large Carcinus maenas have red limbs and undersides rather than the usual green. This is thought to be related to the breeding period (Ditmmann & Villbrandt, 1999) and prolonged intermoult, and is caused by photodegradation of the green exoskeletal pigment. Red morphs of Carcinus maenas were found to have a thicker carapace for greater protection during intraspecific conflict for mates. However, the red morph was also found to have a higher metabolic demand and were less tolerant to changes in salinity and temperature compared to the green morph (Dittmann & Villbrandt, 1999). Green Carcinus maenas are mainly found sheltering under algae where their colour blends-in with the background. Red Carcinus maenas appear brown against a brown background in deep water and are mostly found in the shallow sublittoral where red light does not penetrate. Juvenile Carcinus maenas often have white patches on the carapace to breakup their outline against shell and gravel (Crothers, 1968). In the Wadden Sea and, probably colder, northern parts of Britain, Carcinus maenas migrates to subtidal areas and remains there until spring. During this time the crabs are inactive in shelters and do not feed (Dittmann & Villbrandt, 1999). Lack of prey in the winter also leads to starvation and inactivity (Scott-Fordsmand & Depledge, 1993).
Carcinus maenas is the 1st host of the acanthocephalan helminth Profilicollis botulus which infects eider ducks (Somateria mollissima) by ingestion of infected crabs. Juvenile eider ducks suffer some mortality from heavy infections and crabs are infected by eggs of the parasite from duck faeces(Thompson, 1985).Small Carcinus maenas (3-11 mm CW) can be attacked by the parasitoid platyhelminth Fecampia erythrocephala. This parasitoid is 8-12 mm long and replaces much of the digestive gland in the haemocoel. Infection is usually 1 worm per crab but may be as many as 4. Once the worm is mature it exits the crab, killing it in the process. Prevalence in natural populations is about 7% and Kuris et al., (2002) suggested Fecampia erythrocephala may be a useful biocontrol where introduced Carcinus maenas are a pest because it kills crabs before they can mature and breed.
|Biology References||Crothers, 1968, Dittmann & Villbrandt, 1999, Scott-Fordsman & Depledge, 1993, Klein Breteler, 1975, Crothers, 1967, Ropes, 1969, Walton et al., 2002, Sanchez-Salazar et al. 1987b, Smith, 1907, Naylor, 2000, Thresher et al., 2000, Kuris et al., 2002, Little & Kitching, 1996,|
|Distribution and Habitat|
|Distribution in Britain & Ireland||This ubiquitous crab is found on all shores of Britain and Ireland.|
|Global distribution||North Eastern Atlantic from northern Norway southwards to West Africa. It has been introduced to the USA, Sri Lanka, Red Sea, Madagascar, South Africa and Australia.|
|Biogeographic range||Not researched||Depth range||Intertidal down to 60 m.|
|Distribution Additional Information||No text entered|
|Substratum preferences||No preference
||Physiographic preferences||Open coast
Strait / sound
Ria / Voe
Isolated saline water (Lagoon)
Enclosed coast / Embayment
|Biological zone||Upper Eulittoral
|Tidal stream strength/Water flow||Moderately Strong (1-3 kn)
Weak (<1 kn)
Very Weak (negligible)
|Salinity||Low (<18 psu)
Variable (18-40 psu)
Full (30-40 psu)
Reduced (18-30 psu)
|Habitat Preferences Additional Information|
|Distribution References||Hayward et al., 1996, Hayward & Ryland, 1995b, Fish & Fish, 1996, NBN, 2002, JNCC, 1999, Picton & Costello, 1998, Ameyaw-Akumfi & Naylor, 1987,|
|Reproductive Season||See additional information||Reproductive Location||As adult|
|Reproductive frequency||Annual protracted||Regeneration potential||No|
|Life span||6-10 years||Age at reproductive maturity||1-2 years|
|Generation time||1-2 years||Fecundity||Insufficient information|
|Egg/propagule size||Up to 185,000 eggs.||Fertilization type||Internal|
|Reproduction Preferences Additional Information||Duration of reproductive season is related to geographical location. Egg-bearing females can be found year-round in the south of England, between January and April/May in the Bristol Channel and Wash area and only in spring in northern Scotland (Ingle, 1980).
In areas where there is a defined reproductive season, females aggregate at 'hotspots' and males compete for copulatory opportunities (van der Meeren, 1994). Males preferentially select females with a carapace width 10 mm smaller than their own but are not size selective below this threshold and do not select females on the basis of imminence of moult (Reid et al., 1994). Males 65 mm carapace width or more are large enough to dominate competitive interactions and often mate with several females. However, males of this size only make up approximately 5% of the population (van der Meeren, 1994). Unmated males will try to displace males in precopula (a male carrying a female beneath its body held by one of the legs, prior to the female moulting) and always loses out to a male that has a carapace width 9 mm or larger than its own. Males that are similar size are likely to win intrasex conflicts 50% of the time (Reid et al., 1994).
After moulting the 'soft' female is turned over by the male and copulation ensues through modified pleopods on the much reduced abdomen. As with most crabs, the female bears the fertilized eggs in a mass held between the abdomen and underside of the carapace. Females are berried for up to 4 months, depending on temperature, before the eggs hatch in spring/summer. Females in estuaries migrate to the mouth of the estuary to release larvae at night on ebb tides into fully saline water (Queiroga, 1996). At the southern limit of its range, larvae are released in winter when water temperatures are cooler (Sprung, 2001). Carcinus maenas was reported to breed only at temperatures below 18°C (Crothers, 1967). The maximum fecundity recorded was 185,000 eggs (Crothers, 1967).
|Reproduction References||Queiroga, 1996, Crothers, 1967, Ingle, 1980, Meeren van der, 1994, Reid et al., 1994, Sprung, 2001,|