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Easily seen year round along the Littorina littorea shore line of Burntcoat Class: Gastropoda Head. Order: Neotaenioglossa Family: Littorinidae Genus: Littorina
Distribution The Littorinidae family is a In the genus Littorina is the species L.littorea commonly known group of over 200 known as the edible periwinkle. It is native to the north-eastern coasts species of sea snails, of the Atlantic Ocean, including northern Spain, France, commonly referred to as England, Scotland, Ireland, Scandinavia and Russia and has been periwinkles. They have a introduced to the Atlantic coast of North America. It is now a global distribution. Within predominant mollusc from New Jersey to Newfoundland. In this family of periwinkles Canada, their range includes New Brunswick, Nova Scotia, there are several genera, Quebec, Newfoundland and Labrador. one of which is Litttorina. They are plentiful at Burntcoat Head.
Habitat Though most abundant on rocky substrates and common in tide In the Atlantic it is found pools, it is a habitat generalist that also occurs on muddy or on both open coast and sandy bottoms. They are found along the entire coast, on estuary habitats from the breakwaters, dikes, piers, etc. In favourable habitats, it reaches upper intertidal zone to densities of up to 200-800 individuals per square metre. about 40 metres deep, and Since its arrival in North America it has become the most can tolerate salinities down abundant shallow-water herbivorous snail from Nova Scotia to to around 13 ppt. Long Island Sound.
Food Although primarily an algae grazer, it also feeds on small L. littorea is a mostly invertebrates such as barnacle larvae. They use their radulae to herbivorous, grazing scrape algae from rocks. In salt marshes they pick up algae from intertidal gastropod. cord grass, or from biofilm covering the surface of mud in It feeds on a wide variety of estuaries or bays. algae. L. littorea is oviparous, reproducing annually with egg laying Reproduction timed to coincide with the spring tide; the eggs are released in 1 Breeding may take place mm wide, gelatinous, floating egg capsules, each containing throughout the year; it usually two to three eggs, but sometimes up to nine. The egg tends to vary depending on capsules float in the sea and free-swimming veliger larvae hatch temperature. The sexes are in a few days. Upon leaving the capsules they spend two to six separate (individuals are weeks in plankton. After this approximate six week period spent either male or female), and in the ocean, the larvae settle on the shore. This is referred to as fertilization occurs planktotrophic larval development. Adult females may lay internally after copulation. 10,000 to 100,000 eggs.
Development The columella or central axis of the shell is typically white and Young periwinkles attain the animal is recognizable in its juvenile stages by the transverse sexual maturity at two or black barring of the tentacles which are rather flat and broad. three years of age and may The spiral ridges which are marked in young animals tend to live for five years or more. become obscured in older individuals.
Characteristics A single spiral shell that The shell is sharply conical with a pointed grows with their bodies apex and surface sculpturing. It grows to protects these small snails. a maximum height of 52 mm. The shell The body includes a fleshy colour ranges from grey-black-brown-red foot, a short tail, and two but is generally black or dark grey-brown, antennae on the head. The often lighter towards the apex, and is cream-colored foot is usually patterned with spiral darker lines. divided into a right and a Tentacles are rather flat and broad, with left half, which the snail many transverse black stripes. These stalked moves alternately as the tentacles are sensory organs that are used to muscle ripples forward. see and taste.
Adaptations They can live for many days Periwinkles use their foot to hold without food or water by securely onto rocks when waves retaining moisture in their crash over them or onto marsh gills. They close themselves grasses when the tide rises. When into their shells and excrete using their file-like tongues to feed a sticky mucous that on diatoms and algae they break hardens and firmly attaches down food with mucous on the them to rocks or blades of radula before bringing it into their seagrass. They are able to mouths. adapt to a variety of The pelagic larvae is distributed over environmental conditions, a large area. This can result in the young including extreme heat and periwinkles growing up in an environment wind, low tide, severe wave that is different to that which their parents action, and submergence at grew up in. They are able to survive these high tide. varying conditions. Their generalized characteristics allow them to function in Status/Threats varied circumstances. Predators include a variety of shore birds, fish, crabs and lobsters. They are The common periwinkle was introduced into North America at commercially harvested in Halifax, Nova Scotia, in about 1857 and has spread north to Europe and in North Labrador and as far south as Virginia. It is now the most America in New Brunswick common marine snail along the North Atlantic coast. Although and Nova Scotia, primarily considered to be an invasive species it has become an important in the Bay of Fundy. part in the ecology of rocky intertidal shores.
Sightings in Nova Scotia Prevalent on coastal areas. They are very prolific.