The many physical stresses of ocean life
have encouraged some seaweeds to fill
their cell walls with large quantities of
jelly-like material that gives their tissues
strength and flexibility, can be sloughed
from their surface, and can help keep
coastal species moist when they’re
exposed to the air at low tide. These
special carbohydrates turn out to be
useful for making jellies (agar) and for
thickening various foods (algin,
carrageenan). (More on thickeners in
chapter 11.)Green, Red, and Brown Algae
Nearly all edible seaweeds belong to one of
three broad groups: the green algae, the red
algae, and the brown algae.
Green algae — sea lettuce, awonori —
are the most like the land plants to which