Quahogs can reach a very ripe old age, more than 400 years!. That makes them the oldest animals in the world. However, more than 99% of the quahogs do not come close to growing so old, due to the beam-trawl fisheries. Traces of damage can often be discovered in the year rings.

The Ocean Quahog, or Black Clam (Arctica islandica) is broadly distributed in the boreal-temperate zone of the North Atlantic. It is found from the Barents Sea (Arctic Ocean north of Scandinavia and Russia) to the Gulf of Cadiz (south of Portugal) in the eastern Atlantic (where it is abundant in some regions characterized by important oceanographic fronts, such as Iceland and the boundary between the lrminger and East Greenland currents) (Scourse et al. 2006) and from Newfoundland (Canada) to North Carolina (U.S.A.) in the western Atlantic, where it is a is a common beach shell from Cape Cod northward. It is found in sand at depths from 5 to 500 meters (Scourse et al. 2006). This orange-fleshed clam, which may reach 10 cm in size, is fished commercially to a limited degree from Rhode Island south to Virginia (U.S.A.). (Abbott 1968; Morris 1973; Gosner 1978; Rehder 1981)

The Ocean Quahog may have the longest lifespan of any animal known. These clams mature at 10 to 32 years of age (Abele et al. 2009), but individuals more than 100 years old are common and reported maximum ages from various studies are 225, 268, and 374 years old. Patterns of shell growth in these clams have been used to infer historical climate changes at a range of time scales. (Schöne et al. 2005 and references therein; Scourse et al. 2006; Abele et al. 2008). These clams have also been investigated by researchers studying cellular, molecular, and genetic aspects of aging (Abele et al. 2008, 2009; Bodnar 2009).

 Arctica islandica has a heavy, thick, oval to rounded shell up to 13 cm in length. The shell is sculptured with numerous fine concentric lines and the beaks are anterior. It has a thick glossy periostracum that is brown in smaller individuals, becoming greenish-brown to black in larger specimens. The periostracum peels away on dead shells, revealing a white to pale brown shell beneath.

Arctic Ocean, Atlantic, Bay of Biscay, Belgian Exclusive Economic Zone, British Isles, Clam Cove, Cobscook Bay, Deadmans Harbour, Dutch Exclusive Economic Zone, European waters (ERMS scope), Greek Exclusive Economic Zone, Gulf of Maine, Gulf of St. Lawrence, Hardwood Island, Irish Exclusive economic Zone, L'Etang, North East Atlantic, North Sea, North West Atlantic, Swedish Exclusive Economic Zone, United Kingdom Exclusive Economic Zone, USA, Wimereux

Arctic to Cape Hatteras

Lutz et al. (1982) recorded prodissoconch I lengths ranging from 98 to 118 micrometers in a sample of 50 cultured individuals. Prodissoconch II lengths were found to range between 232 to 289 micrometers in a sample of 100 early post-larval cultured specimens.

Byssal threads are apparently not secreted by early post-larval individuals (Lutz et al., 1982).

The exhalant aperture and siphon develop earlier than the inhalant ones. Mantle fusion delimiting a inhalant aperture occurs when specimens reach a shell length of approximately 1 mm (Lutz et al., 1982).

infralittoral and circalittoral of the Gulf and estuary

Known from rocky shores.

Depth range based on 2638 specimens in 1 taxon.
Water temperature and chemistry ranges based on 1550 samples.

Environmental ranges
  Depth range (m): 0 - 1240
  Temperature range (°C): -0.262 - 22.695
  Nitrate (umol/L): 1.175 - 23.955
  Salinity (PPS): 27.165 - 36.359
  Oxygen (ml/l): 3.835 - 7.573
  Phosphate (umol/l): 0.093 - 1.571
  Silicate (umol/l): 1.808 - 17.288

Graphical representation

Depth range (m): 0 - 1240

Temperature range (°C): -0.262 - 22.695

Nitrate (umol/L): 1.175 - 23.955

Salinity (PPS): 27.165 - 36.359

Oxygen (ml/l): 3.835 - 7.573

Phosphate (umol/l): 0.093 - 1.571

Silicate (umol/l): 1.808 - 17.288
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

 Arctica islandica is found at extreme low water level but predominately on sub-littoral firm sediments including level offshore areas, buried (or part buried) in sand and muddy sand that ranges from fine to coarse grains.

 

The species associated with this article partially comprise the benthic community of Stellwagen Bank, an undersea gravel and sand deposit stretching between Cape Cod and Cape Ann off the coast of Massachusetts. Protected since 1993 as part of the Stellwagen Bank National Marine Sanctuary, the bank is known primarily for whale-watching and commercial fishing of cod, lobster, hake, and other species (Eldredge 1993). 

The benthic community of Stellwagen Bank is diverse and varied, depending largely on the grain size of the substrate. Sessile organisms such as bryozoans, ascidians, tunicates, sponges, and tube worms prefer gravelly and rocky bottoms, while burrowing worms, burrowing anemones, and many mollusks prefer sand or mud surfaces (NOAA 2010). Macroalgae, such as kelps, are exceedingly rare in the area — most biogenic structure along the bottom is provided by sponges, cnidarians, and worms. The dominant phyla of the regional benthos are Annelida, Mollusca, Arthropoda, and Echinodermata (NOAA 2010). 

Ecologically, the Stellwagen Bank benthos contributes a number of functions to the wider ecosystem. Biogenic structure provided by sessile benthic organisms is critical for the survivorship of juveniles of many fish species, including flounders, hake, and Atlantic cod. The benthic community includes a greater than average proportion of detritivores — many crabs and filter-feeding mollusks — recycling debris which descends from the water column above (NOAA 2010). Finally, the organisms of the sea-bed are an important source of food for many free-swimming organisms. Creatures as large as the hump-backed whale rely on the benthos for food — either catching organisms off the surface or, in the whale’s case, stirring up and feeding on organisms which burrow in sandy bottoms (Hain et al 1995). 

As a U.S. National Marine Sanctuary, Stellwagen Bank is nominally protected from dredging, dumping, major external sources of pollution, and extraction of mammals, birds or reptiles (Eldredge 1993). The benthic habitat remains threatened, however, by destructive trawling practices. Trawl nets are often weighted in order that they be held against the bottom, flattening soft surfaces, destroying biogenic structure, and killing large numbers of benthic organisms. There is also occasional threat from contaminated sediments dredged from Boston harbor and deposited elsewhere in the region (NOAA 2010). The region benefits from close observation by NOAA and the Woods Hole Oceanographic Institute, however, and NOAA did not feel the need to make any special recommendations for the preservation of benthic communities in their 2010 Management Plan and Environmental Assessment. 

Stages in the life cycle include a trocophore and a veliger larvae, as in most other bivalves. In larval cultures kept under laboratory conditions, Lutz et al. (1982) recorded a minimum time to settlement of 32 days after fertilization at a temperature of approximately 13 °C; and of approximately 55 days at temperatures between 8.5 and 10°C.

Maximum longevity: 400 years (wild) Observations: These animals show exceptional longevity and have been estimated to live up to 400 years in the wild. One study found that in animals aged 4-192 years, antioxidant enzymes declined rapidly in the first 25 years, which includes the growth and sexual maturity stages, but afterwards remained stable for over 150 years (Abele et al. 2008). Though more detailed studies are warranted, it appears this species is a case of negligible senescence.

The eggs display individual capsules which envelop both unfertilized and fertilized eggs, and are also frequently observed encircling the early cleavage stages, up to at least the 16-celled stage. Eggs are approximately 75 to 90 micrometers in diameter (Lutz et al., 1982).

The sperm possesses unusually long tails (Lutz et al., 1982).

The following is a representative barcode sequence, the centroid of all available sequences for this species.


There is 1 barcode sequence available from BOLD and GenBank.   Below is the sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen.  Other sequences that do not yet meet barcode criteria may also be available.


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Barcode of Life Data Systems (BOLDS) Stats
Public Records: 1
Specimens with Barcodes: 1
Species With Barcodes: 1