B10
Arctica islandica
the longest-lived mollusc in the world

Generally large-size animals have longer age than small ones, but the rule does not always stand strictly. The bivalve Arctica islandica is well-known for its extraordinary longevity, although its shell size is average for common bivalves. The maximum record of the species reported so far in literature is 507 years. Since the species grows extremely slowly, it was difficult to determine its age precisely, but advanced recent technology made it possible to infer a life history in detail. In general, ages of shells with accretionary growth can be determined by a combination of various methods such as (1) culture in aquarium, (2) mark-and-recapture experiment in the field, (3) growth ring analysis in sections of shells, (4) isotope analysis along growth axis, and (5) age-class analysis from size distribution.　(Takenori Sasaki)

References

Butler, P. G. et al. (2013) Variability of marine climate on the North Icelandic Shelf in a 1357-years proxy archived based on growth increaments in the bivalve Arctica islandica. Palaeogeography, Palaeoclimatology, Palaeoecology 373: 141–151.