A Snail Can Sleep For 3 Years...

How I Heard About This: One of my students asked me if snails got tired, it seemed to him that they moved so slowly that they were almost resting. I decided to look up whether they slept at all.
Main Source: http://ezinearticles.com/?A-Snail-Can-Sleep-For-Three-Years---It-is-That-True?&id=1521929
Backup Source: http://www.amusingfacts.com/facts/Detail/snails.html
Topic: Animals/Biology

Details: Snails are members of the mollusk family and need moisture to keep themselves alive. On a very hot day snails will retreat into their shells and wait until night before coming out to eat. When they do retreat into their shells they seal the entrance with a layer of slime that then hardens, leaving only a small hole for air. It has been shown that snails living in particularly dry areas, such as deserts, can hibernate up to 3 years before coming out to find water.