BIOTIC Species Information for Carcinus maenas
|Researched by||Ken Neal & Paolo Pizzolla||Data supplied by||MarLIN|
|Refereed by||This information is not refereed.|
|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,|