Harvesting plants from the sea may be the wave of the future, but many varieties of sea vegetables have been enjoyed since before the development of agriculture. Properly prepared, high-quality sea vegetables are delicious and provide a concentrated source of nutrition.

For centuries, Oriental medicine has recognized that sea vegetables contribute to general well-being and especially to the health of the endocrine and nervous systems. Over the last few decades, medical researchers have discovered a diet that includes sea vegetables reduces the risk of some diseases and helps the body eliminate dangerous toxins. In fact, surveys show that people living in areas where sea vegetables are regularly included in the diet tend to live longer, healthier lives.

One reason sea vegetables are so nutritious is due to the ideal growing conditions of the world's oceans. Living in a marine environment, sea vegetables have ready access to the abundance of nutrients found in the ocean. The gentle wave action of the underwater currents delivers nutrients to sea vegetables and carries away the plants' waste. As a result, sea vegetables concentrate minerals and other nutrients at levels that are rarely found in land plants.

Although biologists classify sea vegetables as plants, the only important characteristic they share with typical land plants is the ability to make food (sugar) from sunlight, carbon dioxide, and water. Both sea and land plants use a light-activated catalytic chemical reaction to accomplish this. In green sea vegetables, like land plants, the catalyst is the green pigment chlorophyll. In red and brown sea vegetables, other pigments predominate. One way scientists classify sea vegetables is by their color. Most of the popular edible sea vegetables, such as wakame, kombu, arame, and hijiki, are classified as brown sea vegetables (algae) while nori, the most widely used sea vegetable, falls under the classification of red sea vegetables. Scientists believe that the different colored pigments allow sea vegetables to make food in the ocean depths, where light intensity and wave lengths are different from those found at the surface.

Beyond the ability to make food, sea vegetables bear little resemblance to land plants. Since they have no true leaves, stems, or roots, and as they reproduce by a primitive method that does not utilize flowers or seeds, sea vegetables are structurally more like mushrooms and other fungi. From a chef's point of view, the simple structure of sea vegetables is an asset. Without woody roots and stems, there is much more to eat.