Terrestrial snails have migrated from water to land and have had to make several adaptations to avoid desiccation.

Respiration:  The original gill of a snail was used to obtain oxygen from only water and not the air. Therefore the terrestrial snail has reduced their gill to help them obtain oxygen from dry air (The Living World of Mulluscs 2011).  The pneumostome or respiratory hole that acts as a lung for the snail has also formed in the mantle cavity to enable air flow for the snail (Hickman et al. 2009).  It is important for terrestrial snail to keep moisture in its mantle cavity to prevent evaporation which could lead to death (The Living World of Mulluscs 2011).

Secretion: Terrestrial snails secrete a hygroscopic slime that attracts water from its surroundings. This adaption has been made by terrestrial snails to help prevent the loss of water and to help them move easier (The Living World of Mulluscs 2011). The secreted mucus also acts like glue when the snail is climbing up a vertical branch or leaf (The Living World of Mulluscs 2011).


Aestivate: Another way terrestrial snails stay moist is to look for suitable conditions during a dry period. This method of adaptation is called aestivating (The Living World of Mulluscs 2011).  Most snails dig into the ground or cling onto plants that hold moisture. Terrestrial snails also close their shells with a mucous covering for protection (The Living World of Mulluscs 2011).


 On the left you can see F. wheatleyi's foot. The foot is out during favorable and not threatening conditions.


On the right you can see the foot is contracted. This happens when the snail feels threatened or to help prevent desiccation.



Jumping: A terrestrial snail also loses water when it moves around so it has developed a technique called “jumping” (The Living World of Mulluscs 2011). When the snail “jumps” it only crawls on certain parts of its foot to prevent losing valuable amounts of water (The Living World of Mulluscs 2011).

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