have a single, coiled shell. A pair of sensory tentacles
come off their head with eyes at the end. Their mouth
has a rasping tongue, called the radula, to shred food.
Most eat plants (including algae) but some eat dead animals.
Parasitic worms may live in them. Snails move by a muscular,
slimy foot under their body. Algae naturally grows on
most aquatic snails. It provides some camouflage.
are both male and female. All snails can lay eggs. They
can "mate" with themselves and thus only one can reproduce
in an aquarium or pond. Most snails lay eggs but some,
like the trapdoor snail, give live birth.
are two types of snails. Gilled snails have gills and
can close their bodies into their shells with a plate,
or door. Gilled snails usually lay their eggs in jelly-like
cocoons above or under water. The trapdoor snail (actually
a livebearer) and apple snail are two of these. Pulmonate
snails have lungs. They either come to the surface to
breathe, or some breathe through their body surface while
underwater. They cannot close their bodies into their
shells. Pulmonate snails usually lay their eggs in gelatinous
masses under water (the Malaysian trumpet snail though
is a live-bearer). Examples are pond snails and ramshorn