The biology and functional morphology ofArctica islandica(Bivalvia: Arcticidae) – A gerontophilic living fossil

Abstract

The North Atlantic bivalve Arctica islandica is a fishery resource and as such there is considerable information about it related to growth, physiology and reproduction. In contrast, however, its form, functional morphology and lifestyle have received scant attention. This study describes the anatomy of A. islandica and provides information to match fossil and rRNA evidence that it is a living fossil probably associated with a Cretaceous heterodont mactrid group adapted to deposit feeding. Arctica islandica lives in buried motionless repose feeding on the carbon-rich seabed surface micro-layer of northern boreal continental shelves. This study concludes that the indolent lifestyle exhibited by A. islandica, along with tissue antioxidant levels sustained into gerontocy, predisposes it to negligible senescence. As a consequence, and as has been demonstrated elsewhere, A. islandica can live for centuries Á the current longevity record being 405 years obtained through an analysis of shell growth rings. Its value, therefore, as a 'tree of the sea', or archival proxy for marine environmental change in the boreal North Atlantic, is not just an appropriate simile with terrestrial tree rings, but an example and reflection of a conservative morphology and simple lifestyle fostering longevity.

Elevated CO2 Levels do not Affect the Shell Structure of the Bivalve Arctica islandica from the Western Baltic

“…The mineral phase present within the shell of A. islandica is aragonite with an outer shell layer (OSL) comprising the outer shell margin and forming the distinct shell increments and growth checks, and an inner shell layer (ISL) extending from the oldest part of the shell, the umbo, to the pallial line [37], [38], [39]. Both layers are separated by a thin myostracum.…”

The Application of Long-Lived Bivalve Sclerochronology in Environmental Baseline Monitoring

“…It is not attached to the substrate, and shows some ability to move vertically through the sediments (Abele, 2002;Morton, 2011), with regular reports of A. islandica burrowing several centimeters into the sediment (e.g., Taylor, 1976;Strahl et al, 2011) and remaining there for periods of several weeks. In respect of food, A. islandica is thought to be very selective, feeding only on fresh organic matter, and discarding older organic material lying at the sediment surface (Erlenkeuser, 1976).…”

Comments on ‘The biology and functional morphology ofArctica islandica’ by Brian Morton,Marine Biology Research, 2011

“…naked mole rats; Andziak et al 2005) provide evidence that ageing rates are retarded in these long-lived species rather than a causative factor in retarded ageing. Morton (2011) seems to have confused causation and correlation. Do stable antioxidants retard ageing, or does retarded ageing cause stable antioxidants?…”

“…In the abstract, Morton (2011) concludes that the indolent lifestyle and antioxidant levels sustained into gerontocy predisposes it to negligible senescence and states stable antioxidant capacities (referring to the stable catalase, citrate synthase activity and glutathione concentrations (Abele et al 2008)) may slow senescence and extend lifespan. While briefly reviewing a sub-section of the literature on antioxidants in bivalves, Morton (2011) further states that high antioxidant capacities (elevated catalase reported by Abele et al 2008) may explain the long lifespan of A. islandica. Recent research demonstrates that such statements are misleading or unsubstantiated.…”

“…In a recent review, Morton (2011) describes the function of the anatomy of the long-lived Arctica islandica (Linnaeus, 1767). In the abstract, Morton (2011) concludes that the indolent lifestyle and antioxidant levels sustained into gerontocy predisposes it to negligible senescence and states stable antioxidant capacities (referring to the stable catalase, citrate synthase activity and glutathione concentrations (Abele et al 2008)) may slow senescence and extend lifespan.…”