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The shell of the snail is largely calcium carbonate. This chemical is familiar to
aquarists as the buffering agent that promotes pH stability. As a consequence of
this, snails generally tend to prefer harder and more alkaline water. In fact, acidic
water tends to dissolve the shell and leave its occupant open to attack from
predators - either to the joy or the horror of the fish keeper.
Apart from their shells, other features that generally distinguish gastropods from
other molluscs is that they have an eye located at the base of each tentacle. The
?foot‘ of the snail is a muscular appendage used to ripple its way across its
environment. Under the tentacles is the mouth. Inside the mouth there is a
rasp-like tongue that acts like a saw. It shreds the snails' food much like a grater
sheds cheese.
This leads me to a topic that may be of interest in the context of the home
aquarium - snails‘ eating habits. The diets of snails vary depending on the
species. Indeed, some snails are carnivorous and will actively hunt down other
gastropods. Generally though, snails eat algae, plants, and on occasion the
decomposing flesh of dead animals.
The Advantages of Snails
The fact that snails eat algae and decomposing flesh can be of great benefit to
the aquarium keeper. I am sure that many of you keep Bristlenoses and other
algae eating catfish. While I do not want to criticise these valued fish, for they do
make fantastic pets in themselves, their algae eating capacities are often over
estimated by their owners. Snails however are very thorough cleaners of glass
and rocks and can get into the nooks and crannies that catfish may miss.
Some species of snail are renowned as decorative plant eaters, however, in my
opinion, only the pond snail should be regarded with any real suspicion in this
regard. Most healthy aquarium plants produce cyanides and other poisons that
prevent animals such as snails from making meals of them. The myth that snails
can destroy your plants probably originates from observations of snails eating
the leaves of plants that are already highly deteriorated or close to dying. At this
point, the plant was probably doomed and at least the snails are preventing the
plant from decomposing, a process that can potentially unbalance aquarium
water chemistry.