Arctica islandica (Linnaeus, 1767)
Ocean quahog
Arctica islandica
photo by Harvey-Clark, Chris

Family:  Arcticidae ()
Max. size:  13 cm SHL (male/unsexed)
Environment:  benthic; marine; depth range 0 - 482 m
Distribution:  Northern Atlantic and the Arctic: from Bay of Cadiz Spain, north to Iceland, and from Cape Hatteras in North Carolina, USA to the Canadian Arctic. Subtropical to polar.
Diagnosis:  Shell: moderately swollen, thick and robust valves, almost circular, equivalved and inequilateral; has a thick dark brown to blackish periostracum; sculpture consists of thin concentric grooves; well-developed external ligament, reaching the end of the posterior margin of the valve, posterior to the umbones; hinge is heterodont, right and left valves each has three cardinal teeth, anterior and posterior lateral teeth; inside the valves are two slightly different muscle scars (dimyarian, anisomyarian), linked by a continuous pallial line (integropalliate), without a sinus; crossed-lamellae structure. Body: pair of gills each consists of two series of lamellae extensively linked by interlamellar junctions (eulamellibranch); foot is large and the two mantle lobes fuse to form two stout siphons.
Biology:  Minimum depth from Ref. 7726. Maximum shell height at 13 cm (anterior-posterior: from the whorl to opposite shell edge) in the Northeast Atlantic. Considered one of the slowest growing clam species in the world and extremely long-lived with an age record of 374 years. As an endobenthic species, population threats include anthropogenic factors such as mechanical damage, oxygen deficiency/eutrophication, unintentional habitat dislocation, temperature and osmotic stress brought by climate change, and, on a major scale, increased trawl fishery in the North Atlantic (Ref. 88171).
IUCN Red List Status: Not Evaluated (N.E.) Ref. 123251)
Threat to humans: 
Country info:   
 

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