Gastropoda ( "Snails & Slugs" )
Meaning of name: "stomach foot" (i.e.. they crawl on their stomach).
This huge group of animals has adapted to most habitats on earth -
land, fresh and saltwater, from the tops of trees to the deepest ocean.
Gastropods evolved greater cephalization over their ancestors, with well-defined
eyes and tentacles, as well as an asymmetrical spiral shell through a process
called "torsion". As with their varied habitats, this group's feeding habits
also vary, from rasping algae-feeders to the highly toxic cone snails that
harpoon their prey.
With over 75,000 species, the variation in shape and shell pattern
in the Gastropoda is enormous.