Marsh Periwinkle Snail
Latin Name: Littoraria irrorata
Species: Marine Invertebrate
Conservation Status: Not Evaluated
These 1-inch snails have a conical shell with a pointed end and are often found near the high-tide line on salt marsh grasses. Their shell is white or gray with spiral ridges, often with reddish dashed streaks. Sometimes these snails are found covered in algae.
Range & Habitat (map)
Marsh periwinkles are found in tidal wetlands along the east coast from New York to Florida and the Gulf Coast to Texas.
Diet
Marsh periwinkles act as farmers. They chew grooves into the grass on which they live and spread waste in these cuts, which then become infected with fungi. The periwinkles then move up and down the stalk throughout the tidal cycle, avoiding predators and grazing on this fungus.
Life History
Marsh periwinkles lay individual eggs just below the surface of the water, which then hatch into free-swimming larvae and develop into small snails in the mid-summer.
Significance
Marsh periwinkles are an important component of salt marsh ecosystems. Their relationship with salt marsh grasses may play an important part in decomposition of these grasses and cycling nutrients back into the ecosystem. Their sensitivity to toxins also make them an indicator species for the health of a salt marsh.
Threats & How You Can Help
The periwinkle snail’s close relationship with salt marsh grasses, particularly Spartina, creates a delicate balance. The increased presence of snails due to reduced populations of blue crabs, one of their major predators, can lead to declines in marsh grasses. Conversely, the reduction of marsh grass abundance or quality can negatively impact snail populations.