Is a Slug Slimier than a Snail? (asked by Anonymous)
Land snails and slugs like the ones you get in your garden are members of the class Gastropoda, along with sea snails, sea slugs and limpets. However, they do not represent distinct branches of the evolutionary tree – slugs are just species of snail that have lost their shell. There are even some snails that have a reduced shell – halfway between slug and snail. So this makes it difficult to answer the question.
However, there are some good reasons why slugs (shell-less snails) might seem to be slimier than their shelled counterparts.