Snails, in general, have adaptations to help them not only survive, but thrive in less than ideal conditions. Many snails are able to seal their soft, moist bodies inside their shell to retain water in times of low rainfall. This mechanism also comes in handy to prevent predation. Predators must exert a significant amount of energy to access the edible portion of the snail, the visceral mass.
Specifically, terrestrial gastropods are able to live because of the development of lungs. In order to get oxygen into the lungs, terrestrial snails have an opening called a pneumostome that is able to open and close via muscular contractions. To help improve locomotion snails on land have gone through shell reduction. This evolutionary process has reduced shell size, making it easier for snails to move (Nordsieck, 2009).