Seaweed

Seaweed refers, loosely, to any of a large number of marine algae, especially those which float near the surface of the water. These are divided among the red, green, and brown algae.

The term is named after terrestrial weed, and not to be confused with seagrass.

Structure

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

• frond[?]: the above sea floor part
  • blade[?]: leaf-like structure that photosynthesize
    • sorus[?]: spore cluster
    • on fucus -- Air bladders: float-assist device (on blade)
  • stipe[?]: stem[?]-like
  • on kelp -- floats: float-assist device (in between blade and stipe)
• holdfast[?]: root-like, anchors to seabed near shore

Values

Some of them are used as food. For example, nori is a red alga dried, 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.