Cockles face many predators - external and internal
John Paul Tiernan
A less-than-common shellfish caught our eyes this week; not on any shore – the weather has been too bad – but stacked in an attractive display inside a doorway on a busy street. Their double-shells and creamy golden ridges suggested confectionery, not at all unlike a very out-of-place mound of Ferrero Rocher. However, the distinctive smell of shellfish and rinsed surroundings of a fish-shop more accurately indicated Cerastoderma edul, or the common cockle, one of Co Mayo’s more inconspicuous shellfish.
The fish-shop owner explained that they had come that morning from one of our many sheltered sandy bays, where like the razor shell, the cockle lives far down the shore near the low-tide mark. There, it lives the typical unexciting life of a sand dwelling shellfish: burrowing into the sand with its only foot for protection and for food, and carrying out the tedious job of siphoning plankton from the water around it through the opening between its two shells.
Besides humans who know where to look, the cockle’s biggest predator is the red-beaked oystercatcher, which despite its name, eats hardly any oysters, but many, many cockles as it over-winters on our shores.
Life is tough for the creamy-coloured cockle; attack also comes from within. The tiny pea crab, a far more ambitious being for its size, makes its home inside the cockle’s shell where it lives quite smartly on the food that the cockle obtains, as well as very cunningly on the cockle’s own living tissue.
The cockle will only be found on a very sheltered shore away from breaking waves with great sandy stretches at low tide, such as Bunnacurry in Achill, inner Clew Bay and Killala Bay. In the east of the country, where many such shores exist, they have a commercial value and are harvested as such. However, on this side of the island the cockle is traditionally caught by hand in spring and early summer, where it may then be used as bait for larger fish or maybe for a cockle soup or roasted over a fire with some butter placed inside.
Far healthier than a Ferrero Rocher, the cockle is low in fat and high in protein and like most shellfish, is a great source of omega-3 oils.
John Paul Tiernan, Louisburgh, runs www.irishmarinelife.com, a website dedicated to the creation of knowledge of our marine ecosystems. He is currently studying for an MSc in Marine Science.