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Water en land

Tidal flats and shallows   Biotope   

Mens en Milieu

Nutrients   Silicon compounds   

Diatoms

size:

up to several tenths of a millimeter

blossoms:

grows quickly and reproduces in the spring

place of growth:

freely in the water or as a layer on the sea floor

characteristics:

tremendous variety in colors and shapes

  • Dut: Kiezelwieren (diatomeeën)
  • Lat: Diatomeae, Bacillariophyceae
  • Eng: Diatoms
  • Ger: Kieselalgen (Diatomeen)
  • Dan: Kiselalger
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Diatoms, Jolanda van Iperen, NIOZ (www.nioz.nl)

Diatoms

Have you ever found flintstone on the beach? You probably didn't realize that the stone was once millions of one-celled diatoms! Diatoms form an important group within the marine phytoplankton. They are capable of fixing lots of energy from the sun, making them an important source of food for plankton feeders, such as worms, copepods and fish larvae. In turn, these small animals are food for larger animals, such as fish. Diatoms make up the base of the food web in the sea. Depending on the species, diatoms live in the water as well as on the bottom of the sea. They don't grow larger than several tenths of a millimeter.

  • A box with a cover
    , NIOZ-Jolanda van Iperen

    A diatom is a box with a cover. These boxes have beautiful shapes, with patterns of holes and dots on the surface. Just like other plankton plants, diatoms can multiply rapidly in a very unique way. The skeleton splits iton two unequal halves and, with the help of special proteins (peptides), each part forms a new silicic shield. After each division, one of the two newly formed algae is just as large as the original cell and the other one is a bit smaller. Eventually as the smaller one multiplies, an infinitely small box results. At that point, the small cell must first grow to a normal size before splitting. Often times, the new cells stick to each other after division, creating chains and ribbons. However, each cell remains independent of the others.

  • Defense

    Copepods are one of the animals that eat diatoms. The diatoms defend themselves by excreting a material which makes the copepods infertile. Scientists think that this material could also be used as medicine for fighting cancer.
    Certain species of diatoms have cadmiun instead of zinc. While it is toxic for humans, these diatoms have no problem with cadmium and can even use it as a 'weapon'.

  • Bottom dwellers
    , Ecomare

    There are also species of diatoms that aren't suspended in the water but grow on the mud flats: the so-called benthic diatoms. They form sugars which in turn form a slimy layer, called an algae film. This layer has a brownish-golden color (see photo) and helps conteract erosion of the flats. The benthic diatoms are the most important 'plants' of the mud flats. They are food for numerous grazing bottom-dwelling animals. Many shellfish, such as Baltic tellins and gapers, have a kind of vacuum slurf to suck up these diatoms from the surface. Without these plants, there would be no ecosystem.

  • Floating ability
    , Jolanda van Iperen, NIOZ

    The floating ability of diatoms is increased by all kinds of protrusions in the form of hairs and thorns. Some species have a drop of oil in their 'box' to increase their floating ability. In addition, the complicated patterns of grooves, indentations and perforations in the boxes also serve to increase the surface area and thereby the floating ability. And finally, a flat cell has a greater capacity to float than a round cell.