Adaptation

Patera leatherwoodi is a terrestrial land snail, so it has experienced many different adaptations throughout it life in order for it to have the capabilities to live out of water.  There is little known about the specific changes that Patera leatherwoodi underwent, so this section will be discussing the changes that the class Gastropoda and terrestrial land snails underwent.

According to Avril Bourguin, the largest change that Gastropods underwent was torsion of their body, Bourguin also describes some of the process of this torsion.  Originally the Gastropods have flat spiraled shells that were very inconvenient for them to move with, for they were so large.  Some of the Gastropods then, experience a twist of 180 degrees in the counter-clockwise direction, this twist then brought the mantle cavity, gills and anal opening to be positioned behind the head.  This torsion now solved the problem of the large symmetrical shell by creating an asymmetrical coil of the shell.  These coils were now stacked, a new one being added below the next.  The coils are also aligned along the center axis known as the columella, which is slightly slanted upwards and backwards, to help compensate for the weight of the shell (Bourguin, 2002).  Although torsion fixed the problem with shell size, it created some different problems, including a compression that resulted in the snails shrinking in size as well as in some cases, completely losing their gill and kidney on the compressed side of the body (Bourguin, 2002).

The sub class of Pulmonata, kept the trait of the torsion (Bourguin, 2002), but they also needed to develop a way to breathe on land.  Nordsieck discusses some reasons as how snails could adapt to terrestrial life, including saving water and in breathing dry air.  Snails originally used gills, that have the capability to acquire oxygen from water, but since the Pulmonates have adapted to live terrestrially, they have modified their mantles to acquire dry air, creating a lung.  The pulmonates also have a problem of losing water through exhaling; this problem is taken care of by multiple adaptations.  The task of protecting the snail’s body from too much water loss is now attributed to the mantle.  The mantle performs its new job by growing into a very thick tissue.  The snails’ have also a ring of muscle that is used to control air flow and water loss through a respiratory hole, known as the pneomostome (Nordsieck, 2011).

The snails in the order of Stylommatophora have increased their fields of vision by placing their eyes at the tops of a second pair of tentacles, known as eye stalks (Nordsieck, 2011).  These sensors are very important to the snails, so all four of its tentacles can be withdrawn into the snail very quickly (Nordsieck, 2011).

 

 

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