Reproduction

This terrestrial, hermaphroditic, snail is sexually active its entire life and is often cued by external factors such as temperature, moisture, duration of light, and population density (Wilbur, 1984). Shell growth with a lip reflection indicates sexual maturity (Wilbur, 1984).

S. barbatum performs a rather long courtship prior to sexual reproduction. Mating most often occurs at night but can happen in the early morning as well (Wilbur, 1984). Increased rainfall (Wilbur, 1984) and favorable weather are known factors to increase mating (Carnegie, 2005). They are known to go long periods of time without mating if the weather is unfavorable (Carnegie, 2005). The courtship begins when each snail excretes mucous through its caudal mucous pores, and they follow each other ingesting one another's mucous, (Wilbur, 1984) which can last up to a few hours (Carnegie, 2005). Throughout this process, the genital pore on the right side of the head behind the right eye tentacle becomes more prominent (Carnegie, 2005). Because this usually happens at night, a snail's limited vision does not come into play (Carnegie, 2005). They use their four antennae, equipped with sensitive chemoreceptors, as well as their touch sensors on their head and foot (Carnegie, 2005). It is unclear whether snails can detect other snails via smell like they can with food; however, they can detect the slime left behind by others (Carnegie, 2005).

The penis and vagina share a common opening called the atrium (Carnegie, 2005). Here is where copulation begins; sperm is transferred via a spermatophore through this genital opening (Carnegie, 2005), using biting with the radial (Fretter & Peake, 1975). This process only takes a few seconds (Wilbur, 1984).

Once inside the other snail, the spermatophore release the sperm (Carnegie, 2005). Sperm and eggs meet in a fertilization chamber where genetic material combines (Carnegie, 2005). After fertilization, the eggs passes down the spermoviduct where they are coated with a jelly-like albumen for vital nutrition and protection (Carnegie, 2005). The eggs are then oviposited, or passed out of the snail's body and into a damp area (Carnegie, 2005).

An adult creates a pocket of soil or beneath leaf litter or decaying wood in order to lay its cleodic eggs, meaning the embryo will develop directly. (Wilbur, 1984). Eggs are laid in permanently moist areas that are rich in calcium so that juveniles can grow a calcium carbonate shell (Wilbur, 1984). Nearly all of the eggs will hatch in 30-45 days (Carnegie, 2005). Though it is unknown yet possible in S. barbatum, cannibalism has been observed in various land species (Carnegie, 2005).

 

Click here to learn about how Stenotrema barbatum interacts with other organisms.

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