lid article she shifted her research focus to other topics,
leaving the blood-suckers to other folks. I will defer to
her profoundly reasonable judgment and refer to all of
these little parasites of who-knows-what species, in who-knows-what genera, as specimens of an indeterminate
species of Turbonilla.
is only one common turbonillid species thoroughout the
Indo-Pacific, or Turbonilla is represented by a small number of very similar species separable only with genetic
analysis, a situation referred to as a species swarm.
Turbonilla, Turbonilla,
Wherefore Art thou, Turbonilla?
Cumming also made a telling statement about the abundance of the species of Turbonilla that she studied and
its natural history. While this species was raising havoc
by parasitizing Tridacna gigas in the aquaculture facility
where she collected them, “No (specimens of)
Turbonilla spp. were found on mature T. gigas in
Pioneer Bay or naturally occurring T. gigas elsewhere on the Great Barrier Reef”
(Cumming, 1993). That point deserves
special notice: in other words, although
this parasite was very abundant in the
one place she collected them, it was essentially unknown, and to the best of
her knowledge had never been seen, anywhere else. This doesn’t mean it doesn’t
exist there, just that if it does, it is very
uncommon and/or hard to find.
As a result of reading these reports,
examining a lot of specimens sent to me
by hobbyists, and examining quite a large
number of species descriptions, I have
become convinced that in the hobby we
are probably dealing with no more than a
couple of species of turbonillids, and that
it is likely that all of the specimens seen
in aquariums belong to a single species. I
have seen some slight differences in the
shell sculpturing of a few of the many
specimens I have examined, which might
be construed to indicate a separate species. However, that difference—a slight
tendency in a few species to show faint
spiral sculpture as opposed to the normal
lack of such sculpturing—is very minor
and may represent nothing more than a
normal within-species variation. Turbonillids are not species-specific parasites,
so individuals of one species can and will
attack any species of tridacnid, probably
any snail species, and possibly any bris-tleworm species they can attach to. It is,
of course, possible that several different
species come into the aquarium hobby,
but I think that is a hypothesis that presently needs a lot of work to confirm. Additionally (and going out on a thin, flexible limb here), I suspect that either there
SpirAled SuckerS
The turbonillids found in aquariums are small, typically
about 1 mm (1/25th inch) wide and a couple of millimeters long. Although at first glance they look like basic
snails, with careful and highly magnified observation
they can be seen to be quite different. Some aspects of
their external morphology are quite aberrant, which they
make up for by being just as weird on the inside. For
their size, they are long and slender snails with many
