Waterwereld
cockle
The cockle is an important shore bivalve living in the mudflats of the north sea.
cockel shell
The cockle has a strong and a rounded heart-shaped bivalved shell with prominent ribs and concentric ridges. The cockle is buried in the sediment so it can’t be scoured out by waves and currents. The cockle’s large, mobile foot allows it to burrow under the surface, but its short siphons mean it can burrow only deep enough just to cover the shell.
The shell of a cockle on the beach
The biggest enemy of the cockle is the the common whelk. The cockle is found by their smell The whelks drills a holes into to the top of the cockle.
Bivalves of the Northsea and baltic sea, printed in 1905, München. J.F. Lehmanns Verlag, as an illustration for "Der Strandwanderer" by P. Kuckuck.
1 European Flat Oyster, Mud Oyster or Edible Oyster or Ostrea edulis
2 Queen Scallop or Pecten opercularis
3 Blue Mussel or Mytilus edulis
4 Common Cockle or Cardium edule
5 Ocean Quahog or Cyprina islandica
6 Venus Clam or Venus gallina
7 Trough-shell or Mactra solida
8 White Furrow Shell or Scrobicularia alba
9 Banded Wedge-shell or Donax vittatus
10 Baltic Macoma, Baltic Clam or Baltic Tellin or Tellina baltica
11 Sword Razor Shell or Solen ensis
12 Soft-shell Clam or Mya arenaria
13 Common Piddock or Pholas dactylus
14 Shipworm ,Teredo worm or Teredo navalis
cockle shell
Cockles are filter feeders, drawing water inside through their gills to get both the food and oxygen they need. Cockles need to be submerged for at least three hours per day for feeding and breating. Cockles remove both plankton and fine minute particles of organic debris and help to keep the water clear.
Cockle fishing is damaging the mudflats and thus the future food supply for many other animals living in these mudflats. Intertidal mudflats are widespread on the Atlantic coasts of Europe, particularly in the large estuaries feeding into the North Sea and around the North sea islands.
cockle and mudflats
Mudflats are those parts of the Northsea that are covered by the sea at high tide and exposed as the tide goes out. They can be found aroumd the Northsea in sheltered coastal inlets, such as harbours and estuaries and around the islands. Mudflats are created because the water movements slow down and allows fine silts and clays to settle from the water onto the seabed. Mudflats are teeming with life especially with worms and bivalves, but also to shore crabs, shrimps and sea snails and a few seaweeds. The worms, like ragworms and lugworms, and cockles and other bivalves live under the surface of the mudflats, protected from the waves and wading birds. Mudflats are hugely important, as they are the larders of the seashore world, providing food for breeding and wintering waterfowl and wading birds. Cockle fishing is damaging the mudflats and thus the future food supply for many other animals living in these mudflats. Other treats are bait-digging, reclamation, pollution and sea level rise.
The cockle forms about 9% of the weight of all the animals living in the Northsea mudflats.
Cockle and and other shells (oysters, mussels) were burnt to produce shell-lime. This lime was widely used in the 19the century, and it is still used today. The spandrels of the domes over the aisles in St Paul's Cathedral, London, were made of brick covered with stucco of cockle-shell lime. This lime is as strong as Portland-cement. A fin du siecle dutch schoolplate.
a tidepool, an illustration of Theo Carreras, 1903. "The world of animal live".
1 strawberry anemone
2 beadlet anemone
3 beadlet anemone
4 cockles
5 common starfish
6 Scallop
7 purple shell
8 periwinkle
9 acorn-barnacles
10 dulse
11 mussel
12 Blackheaded gull