tric tract passes—hence the name, which derives from
the Greek words gaster for stomach and pod for foot.
Snail anatomy has fascinated biologists for centuries, and
controversies still rage, including the one as to why the
anus of a snail is located behind the head, at the front of
the animal, instead of at the rear, where it is positioned
in so many other groups of animals. Snails can retract
their bodies into their shells with astonishing speed, and
many seal the shell opening with a bony plate known as
the operculum to keep predators out. (A snail will also
withdraw completely into its shell when exposed to heat
and dry conditions, such as during low tides.)
Lest we underestimate them, snails do have brains
and are capable of learning to respond to different stimuli. Although slow-moving, snails are not, as popularly
believed, all short-lived. It has been documented that
many species live for six to ten years, and University of
Delaware researchers documented Mud Snails, Ilyanassa
obsoleta, in Rehoboth Bay that were 70 years old. These
snails are sometimes offered to reef aquarists as
Nassari-ous obsoleta, but they are subtropical, omnivorous, and
not reef-safe, as well as being susceptible to premature
death when kept in typical tropical-aquarium temperatures.
The biodiversity of the shelled gastropods is enormous,
and has enabled them to exploit practically every ecological niche that the coral reef and surrounding waters have
to offer. For the curious marine aquarist, observing and
learning more about these snails can provide a whole
new dimension to modern-day reefkeeping.
Turbo parvulus on the aquarium glass demonstrates the
typical mode of locomotion in this genus: the alternate
protrusion of the left and right halves of the foot.
REFERENCES
Mizzaro-Wimmer, M. and L. Salvini-Plawen. 2001. Praktische
Malakologie. Springer Verlag, Vienna.
Knop, D. 2009. Riesenmuscheln—Arten und Pflege im Aquarium.
Dähne, Ettlingen, Germany.
Vittina waigiensis, an algae-eating member
of the Neritidae, is found in
fresh water, brackish water, and
tidal zones.
Cowries—this is the
Tiger Cowrie (Cypraea
tigris)—are among
the best-known
marine snails.
