Mesodon sanus


Mesodon sanus like other land snails are monoecious meaning they have both male and female reproductive organs (Dourson, 2010). These organisms have ovaries, eggs, and an oviduct; and also testes, a penis, and sperm. These snails can have a simple penis or a penis that extends into an epiphallus, which is an enlarged vas deferens (Pilsbry, 1940). They do not have a dart apparatus or “love dart” that other species of land snails often have (Pilsbry, 1940).  
Mesodon Sanus is an air-breathing snail, or a pulmonate (Nature Serve, 2012). Pulmonates differ from prosobranchs, snails with gills, in that pulmonates produce a larger number of eggs in a shorter amount of time (Nature Serve, 2012). Pulmonates also have a life cycle that does not take as long as prosobranch life cycles to complete, and they also grow at a faster rate (Nature Serve, 2012). All of these things generally lead to a more widely dispersed habitat for pulmonates over prosobranchs (Nature Serve, 2012).


In gastropods sperm is transferred in packets called spermatophores, which help the organism to steer clear of self-fertilization (Hickman et al., 2012). Eggs are often laid in holes to avoid contact with predators or on the underside of logs (Hickmen et al., 2012). While terrestrial gastropods go though direct development with no larval stages (as shown in the image below, created by Kelsey Bertelsen using Microsoft Word), the eggs go through two larval stages including a trochophore larval stage and a veliger larval stage (Hickman et al., 2012). In the veliger larval stage the snail goes through torsion (Hickmen et al., 2012). This feature is what separates snails from other mollusks (Hickmen et al., 2012).





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