A cockle is an edible marine
bivalve mollusc. Although many small edible bivalves are loosely called cockles, true cockles are species in the family Cardiidae.[2]
True cockles live in sandy, sheltered beaches throughout the world. The distinctive rounded shells are bilaterally symmetrical, and are
heart-shaped when viewed from the end. Numerous radial, evenly spaced ribs are a feature of the shell in most but not all
genera (for an exception, see the genus Laevicardium, the egg cockles, which have very smooth shells).
The shell of a cockle is able to close completely (i.e., there is no "gap" at any point around the edge). Though the shell of a cockle may superficially resemble that of a
scallop because of the ribs, cockles can be distinguished from scallops morphologically in that cockle shells lack "auricles" (triangular ear-shaped protrusions near the hinge line) and scallop shells lack a
pallial sinus. Behaviorally, cockles live buried in sediment, whereas scallops either are free-living and will swim into the water column to avoid a predator, or in some cases live attached by a
byssus to a
substrate.
The
mantle has three apertures (inhalant, exhalant, and pedal) for siphoning water and for the foot to protrude. Cockles typically burrow using the foot, and feed by filtering
plankton from the surrounding water. Cockles are capable of "jumping" by bending and straightening the foot. As is the case in many bivalves, cockles display
gonochorism (the sex of an individual varies according to conditions),[3] and some species reach maturity rapidly.
The common name "cockle" is also given by seafood sellers to a number of other small, edible marine bivalves which have a somewhat similar shape and sculpture, but are in other families such as the
Veneridae (Venus clams) and the
ark clams (
Arcidae). Cockles in the family Cardiidae are sometimes referred to as "true cockles" to distinguish them from these other species.
Species
There are more than 205 living species of cockles, with many more fossil forms.[4]
The
dog cockle, Glycymeris glycymeris, has a similar range and habitat to the common cockle, but is not at all closely related, being in the family
Glycymerididae. The dog cockle is edible, but due to its toughness when cooked it is generally not eaten, although a process is being developed to solve this problem.[5]
The blood cockle, Tegillarca granosa (not related to the true cockles, instead in the ark clam family,
Arcidae) is extensively cultured from southern
Korea to
Malaysia.[6]
Cockles are a popular type of edible
shellfish in both Eastern and Western
cooking. They are collected by raking them from the sands at low tide. However, collecting cockles is hard work and, as seen from the
Morecambe Bay disaster, in which 23 people died, can be dangerous if local tidal conditions are not carefully watched.
In England and Wales, as of 2011[update], people are permitted to collect 5 kg of cockles for personal use. Those wishing to collect more than this are deemed to be engaging in commercial fishing and are required to obtain a permit from the Inshore Fisheries and Conservation Authority.[7]
Cockles are a
street food in Cambodia where it is usually steamed or boiled and served with a dipping sauce consisting of crushed peppercorns, salt and lime juice.[8]
Cockles are sold freshly cooked as a snack in the
United Kingdom, particularly in those parts of the British coastline where cockles are abundant. Boiled, then seasoned with
malt vinegar and white
pepper, they can be bought from seafood stalls, which also often have for sale
mussels,
whelks,
jellied eels,
crabs and
shrimp. Cockles are also available pickled in jars, and more recently, have been sold in sealed packets (with vinegar) containing a plastic two-pronged fork. A meal of cockles fried with
bacon, served with
laverbread, is known as a traditional
Welsh breakfast.[9][10]
In Japan, the Japanese egg cockle (Laevicardium laevigatum) is used to create torigai sushi.
A study conducted in England in the early 1980s showed a correlation between the consumption of cockles, presumed to be incorrectly processed, and an elevated local occurrence of
hepatitis.[11]
Cockles are an effective bait for a wide variety of sea fishes. The folk song "
Molly Malone" is also known as "Cockles and Mussels" because the title character's sale of the two foods is referred to in the song's refrain. The shells of cockles are mentioned in the English nursery rhyme "
Mary, Mary, Quite Contrary". Cockles are also eaten by the indigenous peoples of North America.[12]
Differing derivations of this phrase have been proposed, either directly from the perceived heart-shape of a cockleshell, or indirectly (the
scientific name for the type genus of the family is Cardium, from the Latin for heart), or from the Latin diminutive of the word heart, corculum. Another proposed derivation is from the Latin for the ventricles of the heart, cochleae cordis, where the second word is an inflected form of cor, heart, while cochlea is the Latin for snail.[citation needed]
References
^Schneider, Jay A. (1995). "Phylogeny of the Cardiidae (Mollusca, Bivalvia): Protocardiinae, Laevicardiinae, Lahilliinae, Tulongocardiinae subfam. n. and Pleuriocardiinae subfam. n.". Zoologica Scripta. 24 (4). Wiley-Blackwell: 321–346.
doi:
10.1111/j.1463-6409.1995.tb00478.x.
ISSN0300-3256.
S2CID86183611.
^Welsh Government.
"Wales.com – Food".
Government of Wales. Archived from
the original on 1 June 2012. Retrieved 24 November 2021. Laverbread, not actually bread at all but seaweed, is rolled in oatmeal, fried into crisp patties and served with eggs, bacon and fresh cockles for a traditional Welsh breakfast.
^"Swansea breakfast recipe - a treat with the taste of the coast". VisitWales. Retrieved 24 November 2021. Swansea breakfast recipe - a treat with the taste of the coast: There's nothing like the smell of cockles and laverbread sizzling away in a pan to bring the essence of the Welsh coast directly to you, wherever you might be.
^
O'Mahony MC, Gooch CD, Smyth DA, Thrussell AJ, Bartlett CL, Noah ND (1983).
"Epidemic hepatitis A from cockles". Drug Metabolism and Disposition: The Biological Fate of Chemicals. 3 (6). NIH: 479–86.
PMID1222. Retrieved 25 March 2006.
Bieler, Rüdiger; Carter, Joseph G.; Coan, Eugene Victor (2010). "Classification of Bivalve families". Nomenclator of Bivalve Families with a Classification of Bivalve Families. Vol. 52. pp. 113–133.
doi:
10.4002/040.052.0201.
S2CID86546840. {{
cite book}}: |journal= ignored (
help)
Herrera, Nathanael D.; Ter Poorten, Jan Johan; Bieler, Rüdiger; Mikkelsen, Paula M.; Strong, Ellen E.; Jablonski, David; Steppan, Scott J. (2015). "Molecular phylogenetics and historical biogeography amid shifting continents in the cockles and giant clams (Bivalvia: Cardiidae)". Molecular Phylogenetics and Evolution. 93: 94–106.
doi:
10.1016/j.ympev.2015.07.013.
PMID26234273.