A cockle is an edible marine bivalve mollusc. Although many small edible bivalves are stewed quail called cockles, true cockles are species in the family Cardiidae. 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.

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. There are more than 205 living species of cockles, with many more fossil forms. 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. 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. In England and Wales, as of 2011, 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. 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. Cockles are sold freshly cooked as a snack in the United Kingdom, particularly in those parts of the British coastline where cockles are abundant. Southeast Asia, and are used in laksa, char kway teow and steamboat. 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. 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”. The common English phrase “it warms the cockles of my heart”, is used to mean that a feeling of deep-seated contentment has been generated. Latin diminutive of the word heart, corculum. European Food Research and Technology, Volume 210, Number 1″. Status of mollusc culture in selected Asian countries”. Cocklers barred from Ribble estuary after coastguard checks”. Street Food Around the World: An Encyclopedia of Food and Culture.