Reproduction

Little is known about specific or unique reproductive habits of the species Fossaria parva, but much can be assumed based on what is known of other species in the subclass Pulmonata.  Almost all freshwater pulmonates are considered hermaphroditic, meaning that each individual organism contains both male and female sex organs (Clifford, 1991).  Fertilization is internal, but usually not a product of self-fertilization.  Self-fertilization occurs when sperm that is produced endogenously within the organism (or autosperm) fertilizes eggs that were products of that same organism.  Although this is a convenient option, pulmonates prefer to have their eggs fertilized by allosperm (sperm donated from another member of the species).  When one member of the species who has mature sperm crosses paths with another, the 'male' (or donator) mounts the shell of the 'female' (or receiver) and orients himself in a way where insertion of a penis is possible.  Upon insertion into the receiver's vaginal canal, the sperm is released and fertilizes the eggs (Dillon, 2000). Once fertilized, the eggs pass through the female reproductive tract, are covered in a gelatinous substance for protection then expelled from the body.  Most of the time, the egg sacs are attached to a solid, aquatic substrate, like a rock or plant.  Once hatched, development is direct, meaning that the young highly resemble their adult parents and there is not a free-swimming larval stage (as there can be in other aquatic gastropods) (Clifford, 1991).

This picture shows an example freshwater snail egg sac.
 

These two pictures (below) show two other species of pulmonates, not Fossaria parva, engaging in sexual reproduction.