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Common Cockle

Cerastoderma edule (Linnaeus 1758)

Biology

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The common cockle is a suspension feeder, filtering plankton and other organic matter from the water (3). The sexes are separate, and adults typically begin to spawn in their second summer. Fertilisation is external, and a large percentage of a population spawns at the same time. Eggs and sperm are released into the water; the free-swimming larvae (veliger larvae) live for 3-6 weeks in the plankton before undergoing metamorphosis into juvenile cockles, which then settle to the substrate. Growth rates vary with the season; in winter there is very little growth, and this leads to the marked growth-bands on the shell, which have been used to age cockles (2). The typical life-span of this cockle is 2-4 years, although they may live for 9 years or more (3). Cockles are predated upon by oystercatchers (Haematopus ostralegus), the shore crab (Carcinus maenas), shrimps and flatfish (2).
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Conservation

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In some areas, concerns about over-collecting have led to measures that control the numbers of cockles harvested and the methods used. In Scotland, for example, dredging with vehicles is banned, and hand gathering is the only method allowed in some parts of England and Wales (2).
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Description

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This well-known edible cockle has a solid shell, consisting of two valves, which feature prominent ribs and concentric growth-lines (2). The outer surface of the shell is off-white, yellowish or brown, and the inner surface is white (3).
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Habitat

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Inhabits the middle and lower shore, where it burrows into soft sand, mud and muddy gravel to depths of less than 5 cm (2). It is often found in huge numbers in estuaries and other sheltered inlets (3).
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Range

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This cockle has a wide distribution around the coastline of Britain. Elsewhere, its range extends from the western Barents Sea and Norway in the north, to Spain and Portugal, and reaches as far south as Senegal in west Africa (2).
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Status

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Common and widespread; not listed under any conservation designations (2).
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Threats

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The common cockle has been collected and sold for hundreds of years. Mechanised forms of collecting, using tractors and hydraulic dredging, have largely replaced more traditional methods such as hand raking. There are fears that without adequate management of cockle stocks, these new techniques could result in over-exploitation (2).
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Brief Summary

provided by Ecomare
Cockles are easy to recognize with their thick ribbed shells. The beach is usually strewn with loose shell halves. They filter plankton out of the water for food, using two siphons. By sticking these siphons out of the sand, they come in contact with the water. A cockle can filter a half liter of water per hour. All together, it takes only a few weeks for the cockles in the mudflats to filter the entire Wadden Sea. Shorebirds and eiders are very fond of cockles, as are some people.
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Diagnostic Description

provided by FAO species catalogs
Shell solid, equivalve; inequilateral, beaks in front of the midline; somewhat broadly oval in outline, with the line of the anterior margin a smooth curve at all growth stages, but the line of the posterior margin becoming less curved in older specimens. Sculptured with 22-28 radiating ribs, each with numerous scale-like spines, and very fine irregular concentric lines. Growth stages prominent. Right valve with two anterior and two posterior lateral teeth. Margin crenulate in front of the anterior lateral tooth to just behind the most posterior lateral, the crenulations continuous with furrows running inside the shell for a short distance only.

Colour dirty white, pale yellow or brown; periostracum yellowish or greenish brown. Ligament a prominent, dark brown, arched band. Inside of shell white, stained brown on and about the posterior adductor scar.

Distribution

provided by FAO species catalogs
From the Barent Sea and the Baltic south to Mauritania, West Africa. Southwestern Mediterranean (rare).

Size

provided by FAO species catalogs
Maximum length is 5,6 cm; common 3 to 4 cm.

Brief Summary

provided by FAO species catalogs
Lives just under the bottom surface on sand, mud and gravel bottoms, intertidal to only a few m deep. The habitats preferred are sandy bays, with some arrival of fresh water. The density of populations can be extremely high: up to 10.000 animals per square meter have been counted.

Benefits

provided by FAO species catalogs
Commercially fished in the British Isles, The Netherlands and France. In Netherlands about 30 ships are specialized in C. eduleand together with a few 2,500,00,000 specimens each year. Caught with bottom trawls and dredges. Marketed fresh and canned.The total catch reported for this species to FAO for 1999 was 70 401 t. The countries with the largest catches were Netherlands, (50 888 t) and UK (14 123t).

Common cockle

provided by wikipedia EN

The common cockle (Cerastoderma edule) is a species of edible saltwater clam, a marine bivalve mollusc in the family Cardiidae, the cockles. It is found in waters off Europe, from Iceland in the north, south into waters off western Africa as far south as Senegal. The ribbed oval shells can reach 6 centimetres (2.4 in) across and are white, yellowish or brown in colour. The common cockle is harvested commercially and eaten in much of its range.

Taxonomy and naming

The common cockle was one of the many invertebrate species originally described by Linnaeus in the landmark 1758 10th edition of his Systema Naturae, where it was given that old binomial name of Cardium edule.[2] The species name is derived from the Latin adjective ĕdūlis "edible".[3] Italian naturalist Giuseppe Saverio Poli erected the genus Cerastoderma in 1795, making the common cockle the type species as Cerastoderma edule.[4] The genus name is derived from the Ancient Greek words keras "horn" and derma "skin".[5] For many years it was referred to by both names.[4]

Other common names in English are edible cockle and common edible cockle.[1] On account of its heart-like shape and its similarity to mussels, it is called the heart mussel in German and Scandinavian languages.[6]

Description

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Cerastoderma edule a) foot b) exhalant siphon c) branchial or inhalant siphon d) edge of mantle e) ligament f) umbones or beaks of the shell

It typically reaches from 3.5 centimetres (1.4 in) to 5 centimetres (2.0 in) in length,[7] but sometimes it reaches 6 centimetres (2.4 in).[6] The shells are pale or whitish yellow, grubby white, or brown.[6][7] The shell is oval, and covered by ribs, which are flattened in the middle part of the shell. The digestive glands are light brown to dark green.[4]

In contrast, the similar lagoon cockle has an elongated shell posteriorly, black digestive glands and is found in substrate of stagnant water.[4]

Distribution and habitat

This species is found in coastal areas of the northern and eastern Atlantic Ocean. It is widely distributed from Iceland and Norway in Europe, to Senegal along the coast of west Africa.[6][7] The common cockle is one of the most abundant species of molluscs in tidal flats located in the bays and estuaries of Europe. It plays a major role as a source of food for crustaceans, fish, and wading birds.

Ecology

This species is a filter feeder, meaning that it feeds by straining water to obtain suspended matter and food particles.[8] Water is inhaled through an inhalant siphon, and exhaled through an exhalant siphon.[7]

It tolerates a wide range of salinity (euryhaline), and wide range of temperatures (eurythermic), which helps to explain its very extensive range. It has a first spawning period in early summer, and a second one in the fall. Lifespan is typically five to six years, though it may perish earlier due to predation by humans as well as crabs, flounder, and various birds especially including oystercatchers.[8] A green shore crab (Carcinus maenas) can consume up to 40 common cockles a day, eating smaller cockles (under 1.5 cm diameter) much more quickly than larger ones. Hence they could have a greater impact in lean seasons where cockles did not grow so quickly.[9]

Parasites and diseases

The cercozoan species Marteilia cochillia is a parasite of the common cockle, having caused a collapse in commercial harvests of cockle beds in Galicia in 2012. [10] A survey of cockle beds in Galicia found that infestation by the gregarine parasite Nematopsis was widespread, and that the most common pathological finding was disseminated neoplasia.[11]

Uses

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Cockle shell ridges imprinted in fragment of Neolithic Cardial ware

These animals were probably a significant food source in hunter-gatherer societies of prehistoric Europe, and the clay remains of shell-imprints have been found. The clay is imprinted with fine decorations, repetitions of the distinct curved ridges, undulating lines and/or edges characteristic to the cockle shell, a natural resource of coastal waters.

Cardial ware is the name of the Neolithic pottery from maritime cultures that colonized Mediterranean shores c. 6000 – 5,500 B.C., this name being based upon the old binomial name of the species: Cardium edule.

In the 1800s, a song called "Molly Malone" was first published (also known as "Cockles and Mussels"), later becoming the unofficial song of Dublin, Ireland. The lyrics describe Molly Malone selling the common cockle in the streets of that city.[6]

As food

This cockle is cooked and eaten in several countries (including the United Kingdom, France, Germany, Ireland, Japan, Portugal and Spain). It is also sometimes eaten pickled, or raw.[6]

An important species for the fishing industry, it is commercially fished in the United Kingdom, Ireland and France by suction dredge (like a huge vacuum cleaner) and also raking by hand. Previously the greatest catch was from the Netherlands, but now fisheries restrictions have been put in place due to environmental concerns. Similar measures have been established elsewhere, for example in Scotland where dredging with vehicles is prohibited, and in parts of England and Wales where only old-fashioned hand-gathering is permitted (using a long plank that is rocked back and forth on the sand).[12]

This species is also used in aquaculture. Farming of cockles is ongoing in the UK, the Netherlands and Portugal. However, production in those countries has not been very stable; for example, production fell from 107,800 tons in 1987 to 40,900 tons in 1997.[13]

Gathering this species can be dangerous. In 2004, the incoming tide at Morecambe Bay in England caused 23 cockle-gatherers to die.[5] In addition to being a food source, their shells have also been used industrially as a source of lime.[5]

See also

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Cockle bed with cockles (Cerastoderma edule) near De Cocksdorp on the island of Texel in the Dutch province of North Holland

References

  1. ^ a b Jan Johan ter Poorten & Serge Gofas (2011). "Cerastoderma edule (Linnaeus, 1758)". World Register of Marine Species. Retrieved April 20, 2011..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
  2. ^ Linnaeus, Carl (1758). Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis (in Latin). Vol. I (10th revised ed.). Holmiae: (Laurentii Salvii). p. 681 – via The Internet Archive.
  3. ^ Simpson, D.P. (1979). Cassell's Latin Dictionary (5th ed.). London: Cassell Ltd. p. 207. ISBN 0-304-52257-0.
  4. ^ a b c d Boyden, C.R. (1971). "A note on the nomenclature of two European cockles" (PDF). Zoological Journal of the Linnean Society. 50: 307–10. doi:10.1111/j.1096-3642.1971.tb00765.x.
  5. ^ a b c Chambers, Paul. British Seashells: A Guide for Collectors and Beachcombers, p. 158 (Casemate Publishers, 2009).
  6. ^ a b c d e f Davidson, Alan. The Oxford Companion to Food, p. 201 (Oxford University Press, 2014).
  7. ^ a b c d Considine, Douglas and Considine, Glenn. Van Nostrand’s Scientific Encyclopedia, p. 2086 (Springer Science & Business Media, 2013).
  8. ^ a b Dauvin, Jean-Claude. Biological heritage and food chains, p. 25 (Quae, Centre de coopération internationale en recherche agronomique pour le développement, 2006).
  9. ^ "The effect of size and temperature on the predation of cockles Cerastoderma edule (L.) by the shore crab Carcinus maenas (L.)". Journal of Experimental Marine Biology and Ecology. 111 (2): 181–93. 1987. doi:10.1016/0022-0981(87)90054-2.
  10. ^ Villalba, Antonio; Iglesias, David; Ramilo, Andrea; Darriba, Susana; Parada, Jose M.; No Couto, Edgar; Abollo, Elvira; Molares, Jose; Carballal, MJ (2014). "Cockle Cerastoderma edule fishery collapse in the Ría de Arousa (Galicia, NW Spain) associated with the protistan parasite Marteilia cochillia". Diseases of Aquatic Organisms. 109 (1): 55–80. doi:10.3354/dao02723.
  11. ^ Carballal, Marıa Jesus; Iglesias, David; Santamarina, Jesús; Ferro-Soto, Beatriz; Villalba, Antonio (2001). "Parasites and Pathologic Conditions of the Cockle Cerastoderma edule Populations of the Coast of Galicia (NW Spain)" (PDF). Journal of Invertebrate Pathology. 78: 87–97. doi:10.1006/jipa.2001.504.
  12. ^ Aikens, Tom. Fish, p. 547 (Random House, 2012).
  13. ^ Spencer, Brian. Molluscan Shellfish Farming, p. 103 (John Wiley & Sons, 2008).
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Common cockle: Brief Summary

provided by wikipedia EN

The common cockle (Cerastoderma edule) is a species of edible saltwater clam, a marine bivalve mollusc in the family Cardiidae, the cockles. It is found in waters off Europe, from Iceland in the north, south into waters off western Africa as far south as Senegal. The ribbed oval shells can reach 6 centimetres (2.4 in) across and are white, yellowish or brown in colour. The common cockle is harvested commercially and eaten in much of its range.

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