Seaweed





Seaweed refers loosely to any of a large number of marine algae considered
by phycologists to be macrothallic (large bodied), differentiated from most
algae that tend towards microscopic size. Seaweeds are found among the
green, red, and brown algae. Some cyanobacteria may also be counted as seaweeds.

Seaweeds are named after terrestrial weeds, and are not to be confused with
things like seagrass which are vascular plants.

Structure

Seaweeds may have an appearance that resembles a non-arboreal terrestrial plants.

   * frond or thallus: the algal body
        o blade: a flattened structure that is somewhat leaf-like
             + sorus: spore cluster
             + on Fucus -- Air bladders: float-assist device (on blade)
             + on kelp -- floats: float-assist device (in between blade and
               stipe)
        o stipe: a stem-like structure
        o holdfast: specialized basal structure providing attachment to the
          bottom

Uses

Seaweeds are used extensively as food by coastal peoples, most particularly
in Japan but also in Korea, in Peru and in the Canadian Maritimes. For
example, nori is a dried red alga, formed into sheets, and used to wrap
sushi. Irish moss is another red alga used in producing various food
additives. Other seaweeds may be used as seaweed fertiliser.