What are they like?
Adaptations specific to the species Mesodon trossulus were quite difficult to find. Therefore, this page provides some general adaptation information on terrestrial snails.
As we know, adaptations are an important part of the evolutionary process. Natural selection helps to maintain adaptive traits in organisms. Adaptations of snails help them in many ways including protection, preservation of water, and locomotion.
Since tererstrial snails do not directly inhabit water, conserving their water proves very important. When snails exhale they lose water. Also, some snails possess a protective structure called an operculum (Hickman, et. al., 2012). The operculum is a hard plate made up of proteins and provides a covering to the opening of the snail’s shell when its body is pulled inside. Ultimately this structure provides protection for the snail and keeps its body from drying out (Hickman, et. al., 2012). The snail's mantle is also a structure that helps to protect against evaporation (Nordieck, 2012). A structure called the pneumostome, which is a key characteristic found in terrestrial snails, is a hole in which air is able to flow into the mantle cavity. Snails are actually able to use this pneumostome to control airflow and water loss by contracting and releasing a small ring muscle (Nordsieck, 2012).
Species in the genus Mesodon exhibit a coiled shell (Pilsbry, 1940). The coiling of the shell occurs simultaneously with an adaption called torsion. During the development of gastropods, this 180 degree twisting of the body causes the anus and mouth to be located in the same area (Hickman, et. al., 2012). Mesodon trossulus and other terrestrial snails developed this adaptaion to increase their protection by decreasing their risk of predation (Hickman, et. al., 2012).
Locomotion is another area where adaptations can be seen in terrestrial snails. The crawling movement of snails is accomplished by their muscular foot. A gland at the front of this foot is responsible for producing a mucus, in which the snail crawls along. This makes it easier for them to crawl and climb over many different types of surfaces (a href="References.htm">Nordsieck, 2012).