Image above is of a Millerelix forfeuillianan shell. Used with permission from Dr. Frank Anderson. (http://mypage.siu.edu/mlcopp/images/spp_images/millerelix_dorfeuilliana.jpg).

Adaptation

Adaptation is very important for all organisms. Without mutations that lead to natural selection, evolution of land snails such as Millerelix forfeuillianan would be nonexistent. One of the most significant adaptations for snails was the development of a vascular mantle for terrestrial snails that became an air-breathing lung known as the pneumostome (Hickman et al. 2012). The pneumostome is controlled by the contraction of the mantle floor (Hickman et al. 2012). This was a very important adaptation for land snails because it allowed marine snails to move from solely aquatic environments to terrestrial environments. Another change that occurred as snails moved onto land was the loss of the larval stages such as the trochophore and veliger larval stage that is seen in marine gastropods (Hickman et al. 2012).

Many of the evolved adaptations occurred to aid in protection against predators. An important structure to Millerelix forfeuillianan is the radula which which can help in protecting their soft body against predators such as Cychrine beetles(Dourson 2010). The radula is the structure on the snail that allows for grinding and scraping of food (Craig et al. 2004) Millerelix forfeuillianan has a head that is a darker color than the body (Walsh et al. 2006). The dorsal side of the foot is nearly the same color as the head and also has a yellow shell (Walsh et al. 2006). This variation in color may help camouflage the snail in leaves on the forest floor of their habit.

Millerelix forfeuillianan can move by using peristaltic contractions of their foot and the pedal gland, which is the mucus producing organ (Hickman et al. 2012). Snails are known for their slow locomotion movements due to the muscles they have available to move their heavy calcium carbonate shell (Hickman et al. 2012). Hickman also states that snails are able to move their shell forward or backward to slightly speed up (2012).

A primary adaptation for all snails is torsion which is the twisting of the body during development (Hickman et al. 2012). This aids in the ability of a snail to retract into the shell for protection also allowing only one hole for a predator to enter when the body is retracted (Hickman et al. 2012). According to Hickman this torsion causes the anus to be located above the mouth which could potentially result in fouling (2012). However, snails have developed the ability to control their bowels (Hickman et al. 2012). Fouling occurs when an organism excretes waste and then ingests that waste(Hickman et al. 2012). Snails also have developed 90^o coiled shells which result in the movement of the nephridiophore as well as the anus to shift right (Hickman et al. 2012). The nephridiophore is an excretory organ that secretes urine (Hickman et al. 2012).

Snails have a complex sensory system. All gastropods have a well developed circulatory and nervous system that have nerves connected by three pairs of ganglia (Hickman 2012). Their sensory organs such as eyes, chemoreceptors, tactile organs and statocysts for balance have helped them to become more successful in terrestrial environments (Hickman 2012). The nephridium helps gastropods to remove access water and metabolic wastes, which is similar to a kidney in humans, but they only possess one of these (Hickman 2012). Millerelix forfeuilliana has two pairs of tentacles; the upper tentacles contain eyes for sight and smell and the lower pair sense food and objects that are close to the ground (Wilber et. al 1964)

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