Marsh periwinkles grow to 1 inch in length. Their spiraling, grooved shell has a slightly pointed spire and varies in color from grayish-white to tan. Reddish-brown flecks appear on the spiral ridges of the shell.


The marsh periwinkle grazes on algae and detritus on the surface of plants and the ground.


Blue crabs, mud crabs and terrapins prey upon marsh periwinkles. It will avoid predators by climbing up marsh grass stalks.

Reproduction and Life Cycle

Marsh periwinkles lay individual eggs into the water. Eggs hatch into free-swimming larvae, which develop into small snails in mid-summer.

Did You Know?

  • A marsh periwinkle uses its gill to get oxygen from the water.
  • Marsh periwinkles are gastropods, a type of mollusk that includes whelks, snails and slugs.
  • These snails are known to practice "fungiculture." By chewing holes in the cordgrass and spreading waste across the cuts, the marsh periwinkle can "farm" fungus, their preferred food.

Sources and Additional Information