Community hub
Recent from talks
Knowledge base stats:
Talk channels stats:
Members stats:
Common periwinkle
The common periwinkle or winkle (Littorina littorea) is a species of small edible whelk or sea snail, a marine gastropod mollusc that has gills and an operculum, and is classified within the family Littorinidae, the periwinkles.
This is a robust intertidal species with a dark and sometimes banded shell. It is native to the rocky shores of the northeastern, and introduced to the northwestern, Atlantic Ocean.
The shell is broadly ovate, thick, and sharply pointed except when eroded. The shell contains six to seven whorls with some fine threads and wrinkles. The color varies from grayish to gray-brown, often with dark spiral bands. The base of the columella is white. The shell lacks an umbilicus. The white outer lip is sometimes checkered with brown patches. The inside of the shell is chocolate brown.
The width of the shell ranges from 10 to 12 millimetres (3⁄8 to 1⁄2 in) at maturity, with an average length of 16 to 38 mm (5⁄8 to 1+1⁄2 in). Shell height can reach up to 30 to 52 mm (1+1⁄8 to 2 in), The length is measured from the end of the aperture to the apex. The height is measured by placing the shell with the aperture flat on a surface and measuring vertically.
L. littorea can be highly variable in phenotype, with several different morphs known. Its phenotypic variations may be indicative of speciation, as opposed to phenotypic plasticity. This is of particular importance to evolutionary biology, as it may represent an opportunity to observe a transitional phase in the evolution of an organism.
L. littorea is oviparous, reproducing annually with internal fertilization of egg capsules that are then shed directly into the sea, leading to a planktotrophic larval development time of four to seven weeks. Females lay 10,000 to 100,000 eggs contained in a corneous capsule from which pelagic larvae escape and eventually settle to the bottom. This species can breed year round depending on the local climate. Benson suggests that it reaches maturity at 10 mm and normally lives five to ten years. while Moore suggests that maturity is reached in 18 months. Some specimens have lived 20 years.
Female specimens have been observed to be ripe from February until end of May, when most are spawning. Male specimens are mainly ripe from January until the end of May and lose weight after copulation. The young seem to settle primarily from the end of May to the end of June,[citation needed] although other sources indicate earlier settlement.
A study in Plymouth Sound suggests an initial growth reaching up to 14 mm (1⁄2 in) in height December the first year, and 17.4 mm (5⁄8 in) by the end of the second year. Females seem to grow more rapidly than males, and in specimens above 25 mm (1 in) in height, females seem to dominate. Another study undertaken in Blackwater Estuary, Essex showed growth reaching up to 8 mm (3⁄8 in) the first winter.
Hub AI
Common periwinkle AI simulator
(@Common periwinkle_simulator)
Common periwinkle
The common periwinkle or winkle (Littorina littorea) is a species of small edible whelk or sea snail, a marine gastropod mollusc that has gills and an operculum, and is classified within the family Littorinidae, the periwinkles.
This is a robust intertidal species with a dark and sometimes banded shell. It is native to the rocky shores of the northeastern, and introduced to the northwestern, Atlantic Ocean.
The shell is broadly ovate, thick, and sharply pointed except when eroded. The shell contains six to seven whorls with some fine threads and wrinkles. The color varies from grayish to gray-brown, often with dark spiral bands. The base of the columella is white. The shell lacks an umbilicus. The white outer lip is sometimes checkered with brown patches. The inside of the shell is chocolate brown.
The width of the shell ranges from 10 to 12 millimetres (3⁄8 to 1⁄2 in) at maturity, with an average length of 16 to 38 mm (5⁄8 to 1+1⁄2 in). Shell height can reach up to 30 to 52 mm (1+1⁄8 to 2 in), The length is measured from the end of the aperture to the apex. The height is measured by placing the shell with the aperture flat on a surface and measuring vertically.
L. littorea can be highly variable in phenotype, with several different morphs known. Its phenotypic variations may be indicative of speciation, as opposed to phenotypic plasticity. This is of particular importance to evolutionary biology, as it may represent an opportunity to observe a transitional phase in the evolution of an organism.
L. littorea is oviparous, reproducing annually with internal fertilization of egg capsules that are then shed directly into the sea, leading to a planktotrophic larval development time of four to seven weeks. Females lay 10,000 to 100,000 eggs contained in a corneous capsule from which pelagic larvae escape and eventually settle to the bottom. This species can breed year round depending on the local climate. Benson suggests that it reaches maturity at 10 mm and normally lives five to ten years. while Moore suggests that maturity is reached in 18 months. Some specimens have lived 20 years.
Female specimens have been observed to be ripe from February until end of May, when most are spawning. Male specimens are mainly ripe from January until the end of May and lose weight after copulation. The young seem to settle primarily from the end of May to the end of June,[citation needed] although other sources indicate earlier settlement.
A study in Plymouth Sound suggests an initial growth reaching up to 14 mm (1⁄2 in) in height December the first year, and 17.4 mm (5⁄8 in) by the end of the second year. Females seem to grow more rapidly than males, and in specimens above 25 mm (1 in) in height, females seem to dominate. Another study undertaken in Blackwater Estuary, Essex showed growth reaching up to 8 mm (3⁄8 in) the first winter.