MOLLUSCS OF BRITISH COLUMBIA

 Class Gastropoda

(Snails, Limpets and Abalones)

by

James A. Cosgrove

The Class Gastropoda (gastro = stomach, poda = foot) is the largest and most diverse class in the Phylum Mollusca.  Containing an estimated 75,000 living species, the gastropods occupy habitats including the terrestrial, marine and freshwater environments.

The most common gastropod is a snail and we think of snails as having a single curved shell.  The gastropods also include limpets and abalones as well as shell-less terrestrial slugs and shell-less marine nudibranchs.

Gastropods generally have a large single foot for locomotion, a mantle that produces the single shell, a single siphon and a well-defined head containing two or four sensory organs that may include rudimentary eyes.  Some terrestrial gastropods have developed pulmonary sacs (lungs) instead of the gills of the marine and freshwater gastropods.

Herbivorous gastropods use their radulas to rasp off plant fragments for food.  Carnivorous gastropods hunt living animals for their food.  In some cases gastropods have developed venomous darts that can be used to kill other animals.  Gastropods such as some members of the Cone Snail group have venom that can be lethal to humans.

As with the bivalves, many gastropods are seen as a food source and some snails are raised in commercial settings.  Also, as with the bivalves, snail shells are highly prized by collectors and may be worth thousands of dollars.