Content on this page requires a newer version of Adobe Flash Player.

Get Adobe Flash player
 

  • Nederlands
  • Deutsch
Search in the Encyclopedia

Dieren en planten

Algae and seaweed   Brown seaweed   Bladder wrack   Knotted wrack   Japanese sargassum   Sea thong   Oarweed   Sea belt   Flora of the sea floor   Seaweeds   

Water en land

Mens en Milieu

  • Dut: Bruinwieren
  • Lat: Phaeophyceae
  • Eng: Brown seaweed, brown algae
  • Ger: Braunalgen
  • Dan: Brun tang
print print

Brown seaweed

Brown seaweeds get their color because they contain a brown pigment which dominates over the green chlorophyll. They are generally large sturdy plants and don't grow in warmer waters. They are tough and easily withstand lots of wave motion. Brown seaweed can form unique underwater habitats. Some species have bladders filled with air, helping them to float or stand up straight. They often wash ashore in large bunches. All kinds of smaller seaweed species and marine animals live among these bunches. There are around eigthy species of brown seaweed found in the Netherlands. Brown seaweed in the flood mark makes good fertilizer for orache species, such as frosted orache.

On Texel


A dozen species of brown seaweed grow here. However, the entire tidal zone is primarily sand and mud, which makes it difficult for seaweed to grow. All kinds of brown seaweed wash ashore, but these are often species that don't grow in the Netherlands. For example, sea-thong (see picture). These seaweeds grow along the coast of the English Channel and drift towards Texel via southwesterly sea currents and wind.

  • Orange seeds
    Sea thong with seeds, Sytske Dijksen, www.fotofitis.nl

    Sometimes, you find seaweed covered with bright orange flecks. The long ribbons have blotches over the entire length. Bladder wrack has flecks on the bladders. When you pick up the seaweed, before you know it, you are covered in orange mush.

    The orange material is seed cells from the seaweed. Seaweed has male seed cells and female egg cells. The seed cells have a small tail, which they use to swim through the water to the egg cell or to creep over the seaweed. If the seed and the egg find each other, a new seaweed plant evolves. You can also find washed up seaweed with egg cells. Since they are practically the same color as the seaweed itself, they aren't as conspicuous.