Andrew,


> I never collect ALL the dead shells, since they form a neat
> little ecologic
> niche in themselves and surely some small creatures depend on them for
> laying eggs, hiding, resting, etc.

It is true that many creatures use empty land snail shells, including other
snails that consume them as a source of calcium. But there are probably
enough empty shells out there to satisfy everyone. The answer to whether or
not one should collect ALL the empty shells depends on the type of research
one intends to do. If one intends to study variation of say, shell
dimensions, in a local population, then one needs to collect all the shells
without discriminating. If the number of empty shells is huge, then a
sub-sample may be collected, but some sort of randomization needs to be
incorporated into the collection scheme to prevent bias from creeping in
(otherwise, one may tend to pick larger shells or shells of a certain
color). One scheme I use when the number of available shells is large is to
collect a predetermined number of adult shells disregarding their dimensions
& other properties. For example, I may collect the first 100 empty adult
shells I find.

On the other hand, if one only intends to know what species lives in a
location, then a few specimens will usually be enough (until the
investigator returns home from the overseas trip, reads the literature &
learns that there are 2 subspecies that differ in size & a larger number of
shells would have been better to pinpoint the subspecies in hand).

> Should private
> collectors be encouraged to work on land snails near their
> homes? It would
> certainly save them a lot of dive money.

YES! Private or professional malacologists can work even in their backyards
(if there are snails). Besides collecting, studies can be done with live
snails, for example, studying mating behavior, food preferences, etc.


Aydin