Periwinkle Shells of the Littorinidae Family

Three Periwinkle Shells of the Littorinidae  Family can be found in this website:

Phylogeny: Periwinkle Shells of the Littorinidae Family are are gastropod mollusks in the Littorinimorpha Order. The superfamily Littorinoidea is one of sixteen superfamilies in this large order. The superfamily Littorinoidea contains three families – Littorinidae, Skeneopsidae, and Zerotulidae. The Littorinidae Family is large and is comprised of three subfamilies, seventeen genera, and two hundred fifteen species. Shells in this family are also commonly known as Winkles and Littorinids.

 Description: Periwinkle Shells are sturdy and ovately conical in shape. They are taller than they are wide. Most are comprised of four to six whorls, which may be rounded or flat-sided. The spire may be moderate to high, and the apex is pointy. The exterior may be smooth, nodose, cancellate (cross-hatched), or sculpted with spiral ridges. The aperture is generally rounded, porcelaneous, and lacking a siphon canal. The columella may be smooth or display teeth.  They lack an umbilicus and a periostracum. Periwinkles have a thin corneous (horn-like) operculum. Periwinkles are very small to medium-sized, with the largest species reaching 5.2 cm ( 2.0 inches ) in height.

Habitat and Distribution: Littorinids are named for the littoral zone (the seashore), along which they reside. They are found attached to mangroves, sea grasses, rocks, seawalls and other hard surfaces. They may be found on exposed coastline or brackish estuaries. They range from above the hightide line to depths of 310 m (1,017 feet). In some areas periwinkles are the most common marine shells found along the coastline. Periwinkle Shells are found worldwide from polar to tropical seas. Fourteen species from this family are found in Mexican waters.

 Natural History: Periwinkle Shells are herbivorous grazers that feed primarily on diatoms, algal film, algae, and other microscopic plant matter. In turn they are preyed upon by shorebirds, fish, and crabs. Periwinkles are gonochoric and reproduce sexually with internal fertilization. The eggs are laid in corneous capsules. Some species of Periwinkle Shells have reduced gills and a vascular mantle cavity which functions as a primitive lung. This gives them the ability to live out of water for weeks without being submerged. Periwinkles are edible and are important foods in Asia and Europe.