View source for Common periwinkle

{{Short description|Species of mollusc}}
{{about|the mollusc|the flowering plant|Vinca}}
{{Speciesbox
| name = Common periwinkle
| image = Sea snail, underneath, full view.jpg
| image_caption = Periwinkle emerging from its shell, [[Sweden]]
| image2 = Littorina littorea 001.jpg
| image2_caption = ''L. littorea'' on the edge of a small sandy beach in [[Woods Hole, Massachusetts]]
| taxon = Littorina littorea
| authority = ([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])<ref>Linnaeus C. (1758). ''[[Systema naturae]] per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.'' pp. [1–4], 1–824. Holmiae. (Salvius).</ref>
| synonyms_ref = <ref name="WoRMS" />
| synonyms = * ''Littorina armoricana'' Locard, 1886
* ''Littorina bartonensis'' Brown, 1843
* ''Littorina communis'' Brown, 1843
* ''Littorina litorea'' (Turton, 1819)
* ''Littorina litorea'' var. ''brevicula'' Jeffreys, 1865
* ''Littorina litorea'' var. ''paupercula'' Jeffreys, 1865
* Littorina litorea var. ''sinistrorsa'' Jeffreys, 1865
* ''Littorina litorea'' var. ''turrita'' Jeffreys, 1865
* ''Littorina littorea'' f. ''intermedia'' Brøgger, 1901
* ''Littorina littorea'' var. ''angulata'' Harmer, 1920
* ''Littorina littorea'' var. ''antiqua'' Wood, 1848
* ''Littorina littorea'' var. ''balteata'' Dautzenberg & Durouchoux, 1912
* ''Littorina littorea'' var. ''complanata'' Harmer, 1920
* ''Littorina littorea'' var. ''conica'' Harmer, 1920
* ''Littorina littorea'' var. ''deformis'' Wood, 1848
* ''Littorina littorea'' var. ''delphinula'' Wood, 1848
* ''Littorina littorea'' var. ''distorta'' Harmer, 1920
* ''Littorina littorea'' var. ''elegans'' Wood, 1848
*'' Littorina littorea'' var. ''fuscofasciatus'' Middendorff, 1849
* ''Littorina littorea'' var. ''major'' Dautzenberg & Durouchoux, 1913
* ''Littorina littorea'' var. ''miniata'' Dautzenberg & Durouchoux, 1900
* ''Littorina littorea'' var. ''pallida'' Dautzenberg & Durouchoux, 1900
* ''Littorina littorea'' var. ''pallidefasciatus'' Middendorff, 1849
* ''Littorina littorea'' var. ''parva'' Harmer, 1920
* ''Littorina littorea'' var. ''picta'' Wood, 1848
* ''Littorina littorea'' var. ''pyramidata'' Wood, 1848
* ''Littorina littorea'' var. ''sanguinea'' Dautzenberg & Durouchoux, 1906
* ''Littorina littorea'' var. ''truncata'' Harmer, 1920
* ''Littorina littorea'' var. ''unicarinata'' Raeymaekers, 1889
* ''Littorina parva'' Teilman-Friis, 1898
* ''Littorina rudis'' var. ''aurantia'' Dautzenberg & P. Fischer, 1925
* ''Littorina rudis'' var. ''reevei'' Harmer, 1921
* Littorina sphaeroidalis Locard, 1886
* Littorina vulgaris J. Sowerby, 1832
* ''Turbo bicarinatus'' Woodward, 1833
* ''Turbo carinatus'' Woodward, 1833
* ''Turbo elongatus'' Woodward, 1833
* ''Turbo litoreus'' Turton, 1819
* ''Turbo littoreus'' [[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]] ([[basionym]])
* ''Turbo sulcatus'' Woodward, 1833
* ''Turbo ustulatus'' Lamarck, 1822
* ''Turbo ventricosus'' Woodward, 1833
}}
The '''common periwinkle''' or '''winkle''' ('''''Littorina littorea''''') is a [[species]] of small edible [[whelk]] or [[sea snail]], a [[marine (ocean)|marine]] [[gastropod]] [[mollusc]] that has [[gill]]s and an [[Operculum (gastropod)|operculum]], and is classified within the family [[Littorinidae]], the periwinkles.<ref name="WoRMS">{{cite WoRMS|author=Vinarski, Maxim|year=2022|title= ''Littorina littorea'' (Linnaeus, 1758)|id=140262|access-date=2011-05-16}}</ref>

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]].

== Description ==
[[File:Littorina_littorea_02.JPG|left|thumb|Shell of the common periwinkle]]

The [[gastropod shell|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 (gastropod)|columella]] is white.<ref name="Benson2009"/> The shell lacks an [[Umbilicus (mollusc)|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 {{convert|10|to|12|mm|frac=8}} at maturity,<ref name="Marlin"/> with an average length of {{convert|16|to|38|mm|abbr=on|frac=8}}. Shell height can reach up to {{convert|30|to|52|mm|abbr=on|frac=8}},<ref name="Marlin">[http://www.marlin.ac.uk/species/detail/1328 Common periwinkle] at marlin.ac.uk retrieved 20.04.2016</ref><ref name="Welch 2010">Welch J. J. (2010). "The "Island Rule" and Deep-Sea Gastropods: Re-Examining the Evidence". ''[[PLoS ONE]]'' '''5'''(1): e8776. {{doi|10.1371/journal.pone.0008776|doi-access=free}}.</ref><ref name="Benson2009"/> 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.<ref name="Eschweiler 2009">Eschweiler, N., Molis, M. & Buschbaum, C. Helgol Mar Res (2009) "Habitat-specific size structure variations in periwinkle populations (Littorina littorea) caused by biotic factors" {{doi|10.1007/s10152-008-0131-x}}</ref>

''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.<ref name="Grahame, J.W.">Grahame J. (1975). "Spawning in ''Littorina littorea'' (L.) (Gastropoda: Prosobranchiata)". ''Journal of experimental marine Biology and Ecology'' '''18''': 185–196.</ref>

=== Life cycle ===
''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.<ref name="Chang 2010" /> Females lay 10,000 to 100,000 [[egg (biology)|eggs]] contained in a [[corneous]] capsule from which pelagic [[larva]]e 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&nbsp;mm and normally lives five to ten years.<ref name="Benson2007"/> while Moore suggests that maturity is reached in 18 months.<ref name="Moore1937">The biology of Littorina littorea. Part 1. Growth of the shell and tissues, spawning, length of life and mortality. Hillary B. Moore,Journal of the Marine Biological Association of the UK, Volume 21, Issue 2, 1937, pages 721-742</ref> 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|date=December 2017}} although other sources indicate earlier settlement.<ref name="Moore1937" />

=== Growth rate ===
A study in [[Plymouth Sound]] suggests an initial growth reaching up to {{convert|14|mm|abbr=on|frac=8}} in height December the first year, and {{convert|17.4|mm|abbr=on|frac=8}} by the end of the second year. Females seem to grow more rapidly than males, and in specimens above {{convert|25|mm|abbr=on|frac=8}} in height, females seem to dominate.<ref name="Moore1937" /> Another study undertaken in [[Blackwater Estuary]], [[Essex]] showed growth reaching up to {{convert|8|mm|abbr=on|frac=8}} the first winter.<ref>Report on the Maldon (Essex) Periwinkle Fishery. F.S. Wright, Great Britain. Ministry of Agriculture and Fisheries. Fishery Investigations. Ser. II, Vol. 14, no. 5 & 6., 1936</ref>

==Distribution==
Common periwinkles are native to the northeastern coasts of the Atlantic Ocean, including northern Spain, France, Great Britain, Ireland, Scandinavia, and Russia.<ref name="Benson2007"/>

There have been more than 14,000 observations made available as a dataset at the Global Biodiversity Information Facility - ''Littorina littorea'',<ref>[https://www.gbif.org/species/2301117 Global Biodiversity Information Facility - Littorina Littorea]</ref> which can be explored. More distribution information can also be found at Ocean Biographic Information System - ''Littorina littorea''.<ref>[http://www.iobis.org/explore/#/taxon/464473 Ocean Biographic Information System - Littorina Littorea]</ref> The NBN Gateway - Littorina littorea has a distribution map over the UK and Ireland.<ref>{{Cite web |url=https://data.nbn.org.uk/imt?mode=SPECIES&species=NBNSYS0000176211 |title=NBN Gateway - ''Littorina littorea'' |access-date=2016-08-08 |archive-url=https://web.archive.org/web/20160822181329/https://data.nbn.org.uk/imt/?mode=SPECIES&species=NBNSYS0000176211 |archive-date=2016-08-22 |url-status=dead }}</ref> These datasets may overlap.

=== Introductions to North America ===
Common periwinkles were introduced to the  Atlantic coast of [[North America]], possibly by [[Ballast|rock ballast]] in the mid-19th century.<ref name="Chapman"/> This species is also found on the [[West Coast of the United States|west coast of the United States]], from [[Washington (state)|Washington]] to [[California]]. The first recorded sighting in the East was in 1840 in the [[Gulf of St. Lawrence]].<ref name="Chapman">Chapman J. W., Carlton J. T., Bellinger M. R. & Blakeslee A. M. H. (2007). "Premature refutation of a human-mediated marine species introduction: the case history of the marine snail ''Littorina littorea'' in the northwestern Atlantic". ''Biological Invasions'' '''9''':737-750.</ref> It is now abundant on rocky shores from [[New Jersey]] northward to [[Newfoundland (island)|Newfoundland]].<ref name="Benson2007" /><ref name="Chang 2010"/> In Canada, its range includes [[New Brunswick]], [[Nova Scotia]], [[Quebec]], Newfoundland and [[Labrador]].<ref name="Benson2009"/>

''L. littorea'' is now the most common marine snail along the North Atlantic coast. It has changed North Atlantic intertidal ecosystems via grazing activities, altering the distribution and abundance of algae on rocky shores and converting soft-sediment habitats to hard substrates, as well as [[Interspecific competition|competitively]] displacing native species.<ref name="Benson2007" /><ref name="Chang 2010"/>

== Ecology ==

=== Habitat ===
The common periwinkle is mainly found on [[rocky shore]]s in the higher and middle [[intertidal zone]]. It sometimes lives in small [[tide pool]]s. It may also be found in [[mud]]dy [[habitat]]s such as [[estuaries]] and can reach depths of {{convert|180|ft|abbr=off|order=flip}}.<ref name="Benson2007"/> When exposed to either extreme cold or heat while climbing, a periwinkle will withdraw into its shell and start rolling, which may allow it to fall to the water.<ref>{{EOL|619396|Edible periwinkle}}</ref>

=== Zone ===
Movement both horizontally and vertically in response to light and dark as well as temperatures have been observed, but over a short timespan the movement seems to be random.

Experiments seem to indicate that the snail responds to light and current, and moves accordingly.<ref>The Biology of Rocky Shores, page 94
By Colin Little, J. A. Kitching</ref>

=== Feeding ===
''L. littorea'' is an [[omnivorous]], grazing intertidal gastropod.<ref name="Chang 2010"/> It is primarily an [[algae]] grazer, but it will feed on small [[invertebrate]]s such as [[barnacle]] larvae. It uses its [[radula]] to scrape algae from rocks and, in the [[salt marsh]] community, pick up algae from [[cord grass]] or from the [[biofilm]] that covers the surface of mud in [[estuary|estuaries]] or [[bay]]s. Macroalgae that are readily consumed include ''[[Ulva lactuca]]'' and ''[[Ulva intestinalis]]'';<ref>The Biology of Rocky Shores, page 83, Colin Little, J. A. Kitching</ref> if provided, [[blue mussel]] can also be eaten.

The radula is taenioglossate, consisting of seven teeth per row: one middle tooth, flanked on each side by one lateral and two marginal teeth. The radula is used to scrape algae and detritus.

[[File:FMIB 48521 Two rows of the radula of Littorina littorea L.jpeg|FMIB 48521 Two rows of the radula of Littorina littorea L]]

[[Phlorotannin]]s in the brown algae ''[[Fucus vesiculosus]]'' and ''[[Ascophyllum nodosum]]'' act as chemical defenses against ''L. littorea''.<ref>Polyphenols in brown algae Fucus vesiculosus and Ascophyllum nodosum: Chemical defenses against the marine herbivorous snail, Littorina littorea. J. A. Geiselman and O. J. McConnell, Journal of Chemical Ecology,1981, Volume 7, Number 6, pages 1115-1133, {{doi|10.1007/BF00987632}}</ref>

=== Parasites ===
The common periwinkle can act as a host for various parasites, including ''[[Renicola roscovita]]'', ''[[Cryptocotyle lingua]]'', ''[[Microphallus pygmaeus]]'' and ''[[Himasthla]]'' sp. More studies are needed before any conclusions regarding the effect of parasites on growth can be reached. It seems that growth rate is primarily affected on available food and time available for feeding, rather than parasites.<ref>Influence of trematode infections on in situ growth rates of Littorina littorea. Kim N. Mouritsen, A. Gorbushin O and K. Thomas Jensen, Journal of the Marine Biological Association of the UK, Volume 79, Issue 3, 1999, pages 425-430</ref>

''[[Polydora ciliata]]'' has also been found to excavate burrows in the shell of the common periwinkle when the snail is mature (above 10&nbsp;mm long). The reason why this happens only to mature snails is not yet known, but one hypothesis is that a mature snail will excrete a signal substance which attracts the ''P. ciliata'' larvae. Another hypothesis is that a mature snail has a change in the shell surface that makes it suitable for ''P. ciliata'' larvae to settle. The infection by this parasite does not seem to alter the growth and proportions of the snail shell.<ref>On the shell growth of Littorina Littorea and the occurrence of Polydora Ciliata. Lars Orrhage, Zoologiska bidrag från Uppsala, Volume 38, 1969, pages 137-152</ref>

=== Mortality ===
A mortality rate of up to 94% per annum has been observed for the first two months, followed by up to 60% per annum for the rest of the first year:

<blockquote>...out of every 950 shells of all ages [collected] at that time, 850 are first year, and 100 are in their second or subsequent year.<ref name="Moore-1937">{{cite journal |last1=Moore |first1=Hilary B. |title=The Biology of Littorina littorea. Part 1. Growth of the Shell and Tissues, Spawning, Length of Life and Mortality. |journal=Journal of the Marine Biological Association of the United Kingdom |date=March 1937 |volume=21 |issue=2 |page=739 |doi=10.1017/S0025315400053844 |bibcode=1937JMBUK..21..721M |s2cid=53869716 |url=https://www.cambridge.org/core/journals/journal-of-the-marine-biological-association-of-the-united-kingdom/article/abs/biology-of-littorina-littorea-part-i-growth-of-the-shell-and-tissues-spawning-length-of-life-and-mortality/A69F04147073EAEFB035D5B301ED0AE5# |access-date=22 November 2022 |ref=moore1937|url-access=subscription }}</ref></blockquote>

Older individuals above 15 months old seem to have a mortality of only 23% per annum. ''[[Cercaria emasculans]]'' is known to be fatal to the snail, but this does not account for the observed mortality.<ref name="Moore1937" />

==Human use==
[[File:Altamira Littorina littorea Édouard Harlé MHNT.PRE.2012.0.609.jpg|thumb|left| Remains of an ancient meal. Winkle shells from [[Cantabria]]n Lower Magdalenian layer (15 000 before present) in the [[Cave of Altamira|Altamira cave]]]]

This species appears in prehistoric shellfish [[midden]]s throughout [[Europe]], and is believed to have been an important source of food since at least 7500 B.C.E. in Scotland.<ref>Ashmore, quoted in McKay and Fowler 1997 b</ref>{{full citation needed|date=April 2024}} It is still collected in quantity in Scotland, mostly for export to the Continent and also for local consumption. The official landings figures for Scotland indicate over 2,000 tonnes of winkles are exported annually. This makes winkles the sixth most important shellfish harvested in Scotland in terms of tonnage, and seventh most important in terms of value. However, since actual harvests are probably twice reported levels, the species may actually be the fourth and sixth most important, respectively.<ref>McKay and Fowler 1997 b</ref>{{full citation needed|date=April 2024}}

Periwinkles are usually picked off the rocks by hand or caught in a [[Trawling|drag]] from a boat. They are mostly eaten in the coastal areas of [[Scotland]], England, Wales and [[Ireland]], where they are commonly referred to as winkles or in some areas buckies, willicks, or wilks. In [[Belgium]], they are called ''kreukels'' or ''caracoles''.

They are commonly sold in [[paper bag]]s near beaches in Ireland and Scotland, boiled in their local seawater, with a [[pin]] attached to the bag to enable the extraction of the soft parts from the shell.

Periwinkles are considered a [[delicacy]] in [[African cuisine|African]] and [[Asian cuisine]]s. The meat is high in [[protein]], [[Omega-3 fatty acid|omega-3]] fatty acids and low in [[fat]]; according to the [[United States National Agricultural Library|USDA National Nutrient Database for Standard Reference]], raw snails in general are about 80% water, 15% protein, and 1.4% fat.

Periwinkles are also used as [[bait (fishing)|bait]] for catching small [[fish]]. The shell is usually crushed and the soft parts extracted and put on a hook.

In accordance with their history as an ancient food source in [[Atlantic Europe]], they are harvested and consumed in the [[Azores Islands]] by the [[Portuguese people]], where they are usually called ''búzios'', the generic name for [[sea snails]].

The record for the farthest a human has spat a winkle was 10.4 metres by Alain Jourden (France) in 2006.<ref>{{Cite book|title=Guinness World Records 2014|last=Glenday|first=Craig|year=2013|isbn=978-1-908843-15-9|pages=[https://archive.org/details/guinnessworldrec0000unse_r3e7/page/221 221]|publisher=Guinness World Records Limited |url=https://archive.org/details/guinnessworldrec0000unse_r3e7/page/221}}</ref>

===Supply chain===
As for seafood supply chains in general, the supply chain consists of a collector, processor, distributor and finally the retailer. The true nature of the supply chain is usually more complex and opaque, with the potential for records of harvesting areas and date of catch to be falsified.
[[File:Common supply chain for periwinkles.svg|thumb|400x400px]]

===Collection===
Commonly harvested in buckets by workers walking in the intertidal zone on low tide; other methods have been tried.

In Maine, the snails are commonly collected by a [[Dredging|dredge]] towed from a vessel.

In Norway, [[snorkeling]] has also been used.

A report on the state of the periwinkle industry in Ireland suggests a maximum catch size in order to preserve the population{{Citation needed|date=December 2017}}.

{{external media
| float  = right
| video1 = [https://www.youtube.com/watch?v=DQldV9upAT4 Dredging for periwinkles], YouTube video
| video2 = [https://www.youtube.com/watch?v=IKqI4Dv7qC8 Snorkeling for periwinkles], YouTube video
}}

===Processor===
The processor buys in bulk from the collector, involving a possibly long transport route by land in a [[refrigerator truck]] or airplane, taking care to avoid temperatures below 0&nbsp;°C.

If fresh seawater is readily available, the periwinkles are first graded if possible, using a machine custom built for the purpose. The method used for grading differs, but two proven methods include a [[Trommel screen]] with horizontal bars instead of a mesh, and a [[circle-throw vibrating machine]] also using bars. The price to purchase a complete sorting machine can be €10,000 or more.

Periwinkles are graded by number of snails per kilogram. The following table displays some common grades in France. The actual value depends upon supply and demand, with seasonal variations. The actual ranges may also differ from each establishment.

{| class="wikitable"
|-
! Grade name
! Number per kilogram
|-
| Small
| Unknown
|-
| Medium
| Unknown
|-
| Large
| 180–240
|-
| Jumbo
| 140–180
|-
| Super Jumbo
| 90–140
|}

After grading, the periwinkles are "climbed" close to the consumer, which involves checking whether they are still alive. This can take anywhere from a few hours to several days, depending on how healthy the periwinkles are and the temperature of the water they climb in. Any periwinkles left immobile at the bottom are considered dead and are discarded. It is not uncommon to have up to 8% waste in a shipment.

[[File:Climbing Periwinkles.svg|thumb]]

Hereafter, the winkles are commonly packed in smaller quantities before being distributed to customers. Mesh bags from 3 to 10&nbsp;kg are common.

===Distributor===
To sell large quantities, distributors are commonly used to move the periwinkles to the retailer. These have networks of transport available both internationally, regionally and locally inside a city. Several distributors are usually involved in the complete journey, each focusing on its own part of the transport network.

===Retail===
The common periwinkle is sold by [[fishmonger]]s at seafood markets in large cities around the world, and is also commonly found in seafood restaurants as an appetizer or as a part of a seafood platter. In some countries, pubs may serve periwinkles as a snack.

Most of the volume fished is consumed by France, Belgium, Spain and the Netherlands.

===Methods to increase commercial value===
Ongrowing has been investigated as a potential way of increasing commercial value, but no documented pilot facilities have been established. By harvesting the periwinkle during the summer and storing them with feed until December, not only should the grade have been increased, but the market value should be higher since supply is lower in the cold winter months.<ref>{{Cite web|url=http://www.seafish.org/media/Publications/SR483.pdf|title=Documents}}</ref>

===Aquaculture===
Raising the common periwinkle has not been a focus due to its abundance in nature and relatively low price; however, there are potential benefits from aquaculture of this species, including a more controlled environment, easier harvesting, less damages from predators, as well as saving the natural population from commercial harvesting.

===Packaging===
Commonly packed in 3&nbsp;kg boxes by the processor, the box is usually [[Polystyrene#Expanded polystyrene (EPS)|polystyrene foam]] or thin wood, depending on the market demands. Holes in the box ensures that any water lost by the snails drains out, so that they remain in better condition for longer. A label indicates the fishing zone, packaging date, and any other information required by law.

===Storing===
In a refrigerator, the common periwinkle can usually be stored for up to a week, but this may vary depending on how long they have been stored prior to sale, and how they have been kept since the moment they are fished. As long as they are kept moist and cold, they can survive well for a longer period of time. It is not recommended to store at temperatures below 0 degrees Celsius, even if research has shown a Median Lower Lethal Temperature of -13.0 degree Celsius.<ref>{{cite journal |last1=Davenport |first1=John |last2=Davenport |first2=Julia L. |date=May 2005 |title=Effects of shore height, wave exposure and geographical distance on thermal niche width of intertidal fauna |url=https://www.int-res.com/articles/meps2005/292/m292p041.pdf |journal=Marine Ecology Progress Series |volume=292 |pages=41–50 |doi=10.3354/meps292041 |bibcode=2005MEPS..292...41D |doi-access=free }}</ref> Even if the common periwinkle survives when put back into seawater, they seem to be unable to move and climb.

== See also ==
* ''[[Tegula pfeifferi]]''

==References==
This article incorporates a public domain text (a [[public domain]] [[work of the United States Government]]) from references<ref name="Benson2007">{{cite web |last1=Benson |first1=Amy |title=Nonindigenous Aquatic Species Database: Littorina littorea |url=https://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1009 |access-date=27 April 2024 |url-status=dead |archive-url=http://web.archive.org/web/20090110064434/http://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1009 |archive-date=10 January 2009 |date=20 August 2007}}</ref><ref name="Benson2009">{{cite web |last1=Benson |first1=Amy |title=Nonindigenous Aquatic Species Database: Littorina littorea |url=https://nas.er.usgs.gov/queries/FactSheet.asp?speciesID=1009 |access-date=27 April 2024 |url-status=dead |archive-url=https://web.archive.org/web/20120223100732/http://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=1009 |archive-date=23 February 2012 |date=21 April 2009}}</ref> and CC-BY-2.5 text from the reference <ref name="Chang 2010">Chang A. L., Blakeslee A. M. H., Miller A. W. & Ruiz G. M. (2011). "Establishment Failure in Biological Invasions: A Case History of ''Littorina littorea'' in California, USA". ''[[PLoS ONE]]'' '''6'''(1): e16035. {{doi|10.1371/journal.pone.0016035|doi-access=free}}''.</ref>
{{reflist}}

== Further reading ==
* Abbott, R. T. (1974). ''American Seashells''. Second edition. New York: Van Nostrand Rheinhold.
* Abbott, R. T. (1986). ''Seashells of North America''. New York: St. Martin's Press.

==External links==
{{Commons category|Littorina littorea}}
{{Scholia}}
* [http://www.issg.org/database/species/ecology.asp?si=400&fr=1&sts Littorina littorea (mollusc)] {{Webarchive|url=https://web.archive.org/web/20110611172023/http://www.issg.org/database/species/ecology.asp?si=400&fr=1&sts |date=2011-06-11 }} from the Invasive Species Specialist Group website of the [[World Conservation Union]]
* [https://web.archive.org/web/20090625055301/http://www.marlin.ac.uk/species/Littorinalittorea.htm Common periwinkle] from the [[Marine Life Information Network for Britain and Ireland]]
* [https://web.archive.org/web/20120219050138/http://webs.lander.edu/rsfox/invertebrates/littorina.html Invertebrate Anatomy OnLine: ''Littorina irrorata''] from a [[Lander University]] website
* {{sealifephotos|140262}}

{{commercial molluscs}}
{{Edible molluscs}}
{{taxonbar|from=Q27935}}

{{DEFAULTSORT:Common Periwinkle}}
[[Category:Gastropods described in 1758]]
[[Category:Commercial molluscs]]
[[Category:Littorinidae]]
[[Category:Marine molluscs of Europe]]
[[Category:Molluscs of the Atlantic Ocean]]
[[Category:Taxa named by Carl Linnaeus]]