By FRED SEITZ — Spring appears to finally have arrived and, with it, some of our more unusual, and sometimes disliked, outdoor critters — snails and slugs. These terrestrial mollusks are often disparaged by gardeners because they eat leafy vegetables, strawberries, beans and citrus fruits, as well as other garden plants. Although snails hibernate during the winter, slugs can remain active, though much of their cold-weather action is underground.
These two beasties are essentially the same; it’s just that snails come with their shell home, which they will retreat into when frightened or threatened.   
Mom Nature chose not to be definitively decisive, as there are also semi-slugs that do not have a snail’s full shell, but rather a small protective partial shell (made of the same calcium carbonate as the full shell) embedded in their skin. Snails, slugs and semi-slugs are all gastropods (gastropod means “belly foot”), which is an apt description of what each one is truly about — a foot which moves along (slowly) and eats.  
Most of the snails and slugs on the East Coast are non-native and came over on plants shipped from Europe. They are usually about half an inch long and live about five years. They can only move about 50 yards an hour.
Snails and slugs are believed to have evolved some 600 million years ago from oceanic mollusks, their aquatic cousins which still exist and are ubiquitous, whether in aquariums and oceans, or in ponds and streams. Even for land snails and slugs, a fair amount of water is essential for survival, and dehydration is a death sentence. In order to maintain a humid environment and reduce their exposure to the sun’s drying rays, they often nestle under boards or rocks laying on the ground. Land snail and pond snail eggs can sometimes be seen on leaves near or in our local bodies of water.
Interestingly, snails and slugs are hermaphroditic, which means they have both male and female reproductive organs. While they are capable of reproducing by themselves, there are also multi-hour courtships involving chemical “communication,” which often result in the fertilization of both participants.
While infamous villains among gardeners, snails and slugs are food for mice, rats, birds, insects, turtles and other snails. They consume dead animals and other decaying material. Snails especially are a famous delicacy for humans, and are reported to be high in protein, low in fat. While I have eaten neither snails nor slugs, those who advocate for their consumption emphasize the importance of carefully cleaning them with multiple boilings and changing the water for each boil. Apparently, their diet may include parasites that can be quite harmful to humans.
There are numerous recipes and instructions for cooking the beasties. And their well-known mucous has reportedly been used for medicinal purposes by Native Americans and others. For more information about these unusual critters, The Secret World of Slugs and Snails by David George Gordon makes for an enjoyable read.