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Dieren en planten

Bivalves   Common cockle   Norway cockle   Prickly cockle   Spiny cockles   Birds   Food availability   Cockles   Bivalves   

Common cockle

size:

maximum 6 centimeters

weight:

0.02 kilogram

color:

white, yellow-brown or brown

age:

maximum 7 years

food:

phytoplankton and organic waste

enemies:

oystercatchers, eiders, gulls, starfish, flatfish, crustaceans, man

reproduction:

sexual

  • Dut: Kokkel (eetbare hartschelp)
  • Lat: Cerastoderma edule (Cardium edule)
  • Eng: Common Edible Cockle (Common cockle)
  • Ger: Essbare Herzmuschel
  • Fren: Coque
  • Dan: Almindelig hjertemusling
print print
Common cockle, foto fitis, sytske dijksen

Common cockle

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.

  • Distribution and habitat
    Cockle burrows itself into the bottom, Sytske Dijksen, www.fotofitis.nl

    Cockles are found mainly in the Wadden Sea and delta region, where the sea bottom is not too muddy. The cockle lives around 5 centimeters deep in the bottom. Young cockles are smaller and can dig themselves in faster and deeper and therefore live even deeper in the bottom, down to 20 centimeters.

  • Cockle population
    Mass cockle death due to warm summer (2006), Ecomare

    The cockle population in the Wadden Sea varies every year in size. During years when there are few cockles, shellfish-consuming birds such as eiders find unsufficient amounts of food. Many birds during such years. Since 2005, fishing cockles with a mechanical vacuum is no longer allowed in the Wadden Sea. The population has been growing since then. In 2008, many older cockles were found in the Wadden Sea, although the amount of young is relatively small. Because there are proportionally few young cockles, it is still unclear how large the total population will be in the coming years.

  • Tapas and paella
    Cockles and whelks in an English fish store, Sytske Dijksen, www.fotofitis.nl

    In the delta waters, it is still permitted in theory to fish cockles mechanically, however it is only allowed to fish them by hand in the Wadden Sea. Cockles are mostly consumed in Spain, Italy and Portugal (tapas and paella). Some people gather their own cockles from the mudflats. It is better to avoid doing that in the summer months (May-August). The cockles, as well as mussels, can contain toxic algae which can make humans very sick.