Nature Bulletin No. 702 January 26, 1963
Forest Preserve District of Cook County
Seymour Simon, President
David H. Thompson, Senior Naturalist
As the number of people in the world increases and the number of acres
of fertile soil to produce food for them decreases, man looks more and
more hopefully at the huge expanses of ocean for relief from hunger.
For ages, fish and other sea foods -- including Seaweeds -- have been
mainstays in the diet of seafaring peoples, islanders and coast dwellers.
Even in the Middle West we are accustomed to eating saltwater fish and
shellfish. Seaweeds, however, are not seen on the vegetable counters of
our stores but, unsuspected by most of us, products of seaweeds are
found in many of our foods, medicines and articles in daily use.
Most seaweeds grow attached to underwater rocks, reefs and the sea
bottom down to depths of 100 feet or more. Although many of them
vaguely resemble flowering plants in size and shape, they do not have
true roots, stems, leaves or flowers. Instead, they are members of that
great group of lower plants called the Algae and should not be confused
with the submersed vegetation in fresh waters, which is sometimes
mistakenly called "seaweed".
The Kelps, largest of the Brown Algae, thrive best in cold water. The
Giant or Vine Kelp with a slender stem anchored to a holdfast in deep
water is reported to reach lengths as great as 1500 feet, making it the
longest plant in the world. Along this stem are many yard-long leaf-like
blades buoyed up by egg-sized floats like stockings hung on a
clothesline. Other kinds of kelp, each with its distinctive shape and
habit of growth, have such colorful names as Devil's Apron, Fan Kelp,
Bull Kelp and Ribbon Kelp.
The Sea Mosses, members of the large group of Red Algae, are delicate
cylinders, sheets, ribbons or feathers seldom larger than a man's hand.
Many are found in deep water where their red pigment enables them to
grow in dim light. The Japanese cultivate certain kinds on bundles of
bamboo in underwater farms. Others are the source of agar used as a
laxative and to make the jelly on which bacteria are grown in
laboratories. Puddings are made from Irish Moss and St. Patrick's soup
from another kind called Dulse.
Seaweeds are rich in many minerals and vitamins necessary for human
health. They add bulk to the diet but are rather poor in fats,
carbohydrates and proteins. Formerly, they were an essential source of
iodine and potassium. More recently an industry in California, using
mechanical harvesters mounted on barges, processes kelp into a number
of useful products. Among these is a substance called "algin" which
gives body to other substances. It prevents the chocolate from dropping
to the bottom of your chocolate milk and keeps your ice cream from
rapidly melting into a puddle. n is used in shaving cream, shoe polish,
lipstick, shampoo, cosmetics, lubricating jellies and as sizing in cloth.
Kombu is a food prepared from seaweed by the Japanese for use in
soups, on meat and rice, or nibbled after crisping over a fire. As a
result, because of its iodine content, goiter is almost unknown there. In
the Scandinavian countries and the British Isles, herdsmen near the
coast feed seaweed to their cattle or graze their sheep on it at low tide.
In Ireland potato fields are fertilized with kelp.
In 1492 Columbus sailed into a vast expanse of floating seaweed, much
to the terror of his men who imagined that this was the legendary
graveyard of becalmed ships. This Sargasso Sea, with its unattached
Gulf Weed, covers an area as large as the United States, extending half
way across the Atlantic east of Florida and the West Indies.
Some sea serpents may be nothing more than large kelp seen in dim
light by sailors after a night in port.
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Update: June 2012