>Just a question : In almost all living animals is possible to know or al least
>presume the age of the specimen. With shells ... how it works ? Is there a
>relation between size and age ?  Has someone done a research (size / growing /
>age) or I am dreaming about it ? Thank you

If the shell lives in an environment with sufficient seasonal variation,
there will be patterns similar to the rings in trees.  For example, many
species in cooler climates have slow growth in the winter, reflected in the
structure of the shell.  Microscopic analysis of the pattern of growth
bands can help study this, as can analysis of isotope ratios (influenced by
temperature and other environmental factors) in samples taken along the
shell.  Doug Jones, at the Florida Museum of Natural History, has done a
lot of work on this.  Arctica islandica may be as old as 200 years, and
Margaritifera nearly as old, but Tridacna is actually very fast growing and
not extrordinarily long-lived.


Dr. David Campbell
"Old Seashells"
Department of Geological Sciences
CB 3315 Mitchell Hall
University of North Carolina at Chapel Hill
Chapel Hill NC 27599-3315 USA
[log in to unmask], 919-962-0685, FAX 919-966-4519

"He had discovered an unknown bivalve, forming a new genus"-E. A. Poe, The
Gold Bug