Are all seaweeds edible?

Question

if not, about how many kinds are edible?

Answer 1

No, not all seaweeds are edible. You may need to dig around for lists for lists of edible seaweeds. Here's the link for one particularly interesting looking book:

http://seagrant.uaf.edu/bookstore/pubs/S...

Here's another potentially useful article from the primary literature:

http://www.sciencedirect.com/science?_ob...

Answer 2

Good question. This is a useful link too describing edible seaweed species that a brief quote here is in order, in a minute.

Seaweeds are found throughout the world's oceans and seas and none is known to be poisonous.

One more quote here, hold on. Second link there, 110 species are edible of thousands of species. There is a broader page clicking on "seaweed aquaculture" but this page is better.

The main food species grown by aquaculture in these countries are Nori or Zicai (Porphyra, a red alga), Kombu, Kunbu or Haidai (Laminaria or Saccharina: brown algae) and Wakame (Undaria, also a brown alga). In Japan alone, the total annual production value of nori amounts to >US$2 billion, one of the most valuable crops produced by aquaculture in the world.

Now if you click on that word aquaculture you get more information.