Seventy-one percent of the earth's surface is covered by oceans. In all of those oceans are a variety of marine algae, better known as seaweeds. Categorized in three color groups - red, brown, and green - they are not completely classified and their diversity is not fully understood. There are believed to be about 10,000 kinds and “they are essential to the life of the planet,” with 75% of the oxygen we breathe being supplied by marine algae.

Seaweeds are significant in the history and culture of numerous countries, with some references going back thousands of years. They appear in the Epic of Gilgamesh, where Gilgamesh weighted himself down with stones to reach the bottom of the sea where he secured a plant (seaweed) that he believed would make people immortal. But the seaweed was stolen and consumed by a snake, which now can shed its skin and grow a new one. People can't do this, so they must die because Gilgamesh lost the seaweed.

Ancient Greek societies were suspicious of the ocean and feared seaweed. The Greek sea god, Pontus, was portrayed with hair consisting of seaweeds that trapped and drowned sailors. But not all Greeks feared seaweed. Pliny the Elder wrote that seaweed applied to the body could relieve gout and lessen ankle pain and swelling. Ninth century Arab physicians also used seaweeds medicinally to treat cancer, cirrhosis, kidney problems, arthritis, hemorrhoids and other conditions. Arabs also covered their ships with a non-flammable brown seaweed extract, thus saving the ships from being burned by enemies.

In Japan, seaweeds are considered “our way of eating.” Some people eat seaweed at every meal, with the most popular species being wakame, nori, and kombu. Ancient Japanese poetry is filled with references to seaweed. In China, use of seaweed started historically as a medicine. A complex system, Huangdi Neijing (Classic of Internal Medicine), has changed greatly since its origin about 200BC. The author of Seaweed provides an interesting explanation of normal health and how medicines, including seaweed, are used to treat illness in this complicated system. Additionally, a table provides a description of the “Eight Main Methods used to Prepare Seaweed in China.”

The examples given are just a few of the fascinating stories about seaweed in this book. Other interesting accounts include ways that seaweeds impacted history and culture, e.g. When Columbus crossed the Atlantic Ocean in 1492, 23 days of his 35 day voyage were spent in the Sargasso Sea, where the “floating seaweed was so thick it resembled meadows.” The Wampanoag of Massachusetts, alternating between land and seashore, prepared apponaugs, seafood feasts where seaweeds were used in the cooking. In 17th century Ireland, the Crith Gablach, a set of hospitality rules, required that, if people of status came to one's home, dulse was to be offered to them. Seaweed was an important part of the diet on coastal Scandinavia and it was a valuable provision on Viking voyages.

An afterword to the book suggests that “the future is seaweed.” Already seaweeds are used in the cosmetics and toiletries industries, food processing, furniture care products, paints, dyes, fire-fighting foam, soil conditioners, and bioplastics. Possible future uses of seaweeds include agricultural products, pharmaceutical products, and perhaps even a source of “green energy.” An article in New Yorker magazine stated that “seaweed could be a miracle food - if we can figure out how to make it taste good.”

Though limited in the biological features and heavy on the historic and cultural aspects of seaweed, the short captivating book is fun to read and is a treasure trove of fascinating information. It is part of a large book series called “Edible,” published by Reaktion Books. A special feature is a selection of recipes for various seaweeds. The narrative is thoroughly researched, featuring a comprehensive list of references. It also contains a list of print and online resources and a modest index.

AMANDA L. GLAZE is an Assistant Professor of Middle Grades & Secondary Science Education at Georgia Southern University in Statesboro, Georgia. In addition to science teacher education, she has taught courses in biological sciences for grades 7–12 and undergraduate students over the last ten years. Her interests include evolutionary biology, science and religion, and the intersections of science and society—specifically where scientific understandings are deemed controversial by the public. Glaze holds degrees in science education from The University of Alabama and Jacksonville State University. Her address is Department of Teaching & Learning, Georgia Southern University, PO BOX 8134, Statesboro, GA 30458; e-mail: aglaze@georgiasouthern.edu.