Seaweed Is Not a Weed: Why the Ocean's Algae Matter So Much

"Seaweed" is a misleading name. A weed is a plant that spreads so aggressively it harms the place where it grows — kudzu, the infamous "mile-a-minute vine" that chokes waterways across the U.S. Southeast, is the classic example. Seaweeds are the opposite. They are essential to countless marine creatures as food and habitat, and useful to people in more ways than most realize.

A kelp forest in the Channel Islands National Marine Sanctuary and National Park. Credit: NOAA.

What seaweed is

"Seaweed" is the common name for countless species of marine plants and algae that grow in the ocean and in rivers, lakes and other waters. They come in every size:

• Microscopic, like the phytoplankton that drift in the water and form the base of most marine food chains.
• Enormous, like the giant kelp that grows in forests and towers like underwater redwoods.
• Medium, like most seaweeds — red, green, brown or black, and washing up on beaches just about everywhere.

Food

Seaweed is full of vitamins, minerals and fiber, and it can be delicious. For at least 1,500 years the Japanese have wrapped raw fish, sticky rice and other ingredients in a seaweed called nori: the sushi roll.

Medicine

Many seaweeds contain anti-inflammatory and antimicrobial agents, and their medicinal use goes back thousands of years. The ancient Romans used them to treat wounds, burns and rashes, and anecdotal evidence suggests the ancient Egyptians may have used them to treat breast cancer. Some seaweeds contain powerful cancer-fighting agents that researchers hope will one day prove effective against malignant tumors and leukemia.

Industry

Seaweeds also contribute to the economy. In manufacturing they are effective binding agents (emulsifiers) in products like toothpaste and fruit jelly, and popular softeners (emollients) in organic cosmetics and skin care.

Sources

Based on "What is seaweed?" from NOAA's National Ocean Service, a work of the United States government in the public domain.