By George Ellison with illustration by Elizabeth Ellison
“Land snails can be considered one of the many building blocks for the ecosystems in which they reside, providing not only a food source but accessibility to calcium, often a rare commodity in the Southern Appalachians.”
~Dan and Judy Dourson, Land Snails of the Great Smoky Mountains (2006)
Land snails can’t sing, and they can’t fly, but they do have something in common with birds. Both are “calcifiles”—that is, each is dependent upon significant amounts of calcium for survival. Snails need it to construct and maintain the elaborate housing they tote around on their backs. Birds need it to construct the eggs in which their offspring are gestated.
Land snails are terrestrial gastropods in the phylum Mollusca. They are a diverse group numbering upwards of 100,000 species worldwide. Five hundred or so species have been documented in eastern North America. About 150 of these occur in Great Smoky Mountains National Park.
Slugs aren’t snails that have crawled out of their shells. They are unsightly terrestrial gastropods whose shells are either undeveloped or entirely absent.
The land snail is a marvelous critter to behold. Trending either clockwise or counterclockwise, the shells of some species rival those of seashells in regard to both design and color.
They move by muscular contraction of a large “foot.” A series of as many as ten waves at a time pass up the sole of the foot. Each shows up as a dark band that seemingly indicates electrical stimulation of some sort.
As depicted in Elizabeth's illustration, land snails have two pairs of tentacles. The tallest have eyes at their tips. This allows a wider frame of vision because they're able to move them around by manipulating the tentacles. The shorter pair provide a sense of smell.
Land snails don’t move at warp speed; they make box turtles and toads look like speed merchants. But neither do they stumble and bumble around in their Lilliputian world of mosses, twigs, and pebbles. They glide like miniature sailboats—veering gracefully this way and that on tracks of slimy mucus they secrete that can be adjusted according to the smoothness or roughness of the surface being traversed.
Where can you observe land snails in the Great Smokies? Just about every- where at all elevations in which moist shady conditions prevail. Dan and Judy Dourson note that, "The base of large diameter tree species such as black and butternut walnut can sometimes yield high numbers of land snails.” Clusters of leaves that lodge in the forks of a tree are favorite hideaways.