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Acorn barnacle


each 5 to 10 millimeters in diameter




maximum 8 years old




worms, snails, starfish, some fish, birds



  • Dut: Gewone zeepok
  • Lat: Semibalanus balanoides
  • Eng: Acorn barnacle
  • Ger: Gemeine Seepocke
  • Dan: Almindelige rur
  • Bel: Zeepuist
Common barnacle, foto fitis, sytske dijksen

Acorn barnacle

The acorn barnacle is the most prevalent barnacle along the North Sea coastline. These barnacles look like flat cones. The animal itself lives in this six-sided cone. Within the cracks and crannies of rocks, dikes or whatever they land on, they are often so squished in between their neighbors that they are forced to grow upwards. An unusual fact: larvae of the acorn barnacle living in waters which freeze near the North Pole, are caught in the ice and also freeze. However, they can survive life as an ice cube for several weeks; once they defrost, they just move on with life.

  • Distribution and habitat
    Barnacles in ice, foto fitis, sytske dijksen

    The common barnacle can attach itself to anything hard and found in the tidal zone, such as stones, shells and larger animals such as crabs. They will also grow on moving animals and objects, such as buoys,ships and wrecks. The house of the acorn barnacle is not calcified at the base, meaning that it doesn't leave a trace on its underground. It breeds in late autumn. brooding the eggs till February.