>Papers on growth is scattered throughout the literature.  Most writers
>deal with only one family, or one species.  Many books give a general
>treatment on growth.  Does anyone have a book dealing with growth as the
>major topic?                     Aloha from Wesley M. Thorsson


Hello,

Wesley gave a good explanation on the topic that is very complex and difficult to answer.
I would like to add one thing that is often overlooked or ignored in literature on growth and
age of molluscs. Most shelled molluscs develop as pelagic larvae that settle at very small
sizes, that is a shell length from one tenth to a few millimeter, depending on the species.
It takes a while, often up to one year or more, for juvenile molluscs to grow to attain large
enough size to be visually recognized. Thus, even professional researchers tended to
underestimate the juvenile age from their size, mistaking such juveniles as those just settled.

I have raised several species of both bivalves and gastropods from eggs to large juveniles
or adults and found that the initial growth tended to be very slow (though the growth curve
is close to be exponential - accelerating as the size increases, just like a human embryo
developing to a fetus). Therefore, the first year of molluscan age can easily be ignored
in the field studies where it is very difficult to catch very small juveniles less than several
millimeters. Even if the age of a shell can be read by counting annual rings, the first ring
might be overlooked.


Masashi Yamaguchi
e-mail: [log in to unmask]
Faculty of Science,
Univ. of the Ryukyus