Predators play of course an important role in the ecology of snails, and various groups have developed their own strategy during the evolutionary process to try to fence off their enemies. Simone just published an overview of these strategies in South American land snails in a new (privately run) digital journal, which he called ‘Malacopedia’.
Unfortunately, the website of the journal seems out of order, so I cannot provide a direct link to the paper.
In his paper he discusses apertural barriers, changes in the direction of shell growth, hyper-coiling of the shell, hyper-retraction of the animal, alterations of size, and sinistral coiling.
This review seems to me a useful start, as the topic has been treated in literature mainly regarding marine and freshwater species. The ecology, biology and life cycle aspects of land snails have received comparatively little attention, and further studies on this topic may be interesting. Especially when they are not limited to the Neotropical realm only.
Simone, L.R.L., 2018. Physical defence strategies of South American land snails. – Malacopedia, 1: 3-11.