- Any of numerous marine algae, such as a kelp, rockweed, or gulfweed.
- Any of various marine plants.
Dictionary:
sea·weed (sē'wēd') ![]() |
| Food and Nutrition: seaweed |
Marine algae of interest as food include Irish moss, laver bread, and kelp, which are eaten to some extent in different communities and serve as a mineral supplement in animal feed.
| Food Lover's Companion: seaweed |
An important food source in many Asian cultures, seaweed is a primitive sea plant belonging to the algae family with origins dating back millions of years. Japanese cuisine employs different varieties (such as kombu, laver and nori) for many uses including soups, vegetables, tea, sushi and as a general seasoning. The Irish are partial to the seaweed known as carrageen, and agar is widely used throughout Asia. Seaweed is a rich source of iodine, an important nutrient. Many seaweeds also provide alginic acid, a jellylike substance that's used as a stabilizer and thickener in a wide variety of commercially processed foods such as ice creams, puddings, flavored milk drinks, pie fillings, soups and syrups. See also dulse; hijiki; kelp; limu; wakame.
| Britannica Concise Encyclopedia: seaweed |
For more information on seaweed, visit Britannica.com.
| Columbia Encyclopedia: seaweed |
Types of Seaweed
The simplest of the seaweeds are among the cyanobacteria, formerly called the blue-green algae, and green algae (division Chlorophyta), found nearest the shore in shallow waters and usually growing as threadlike filaments, irregular sheets, or branching fronds. The brown algae (division Phaeophyta), in which brown pigment masks the green of the chlorophyll, are the most numerous of the seaweeds of temperate and polar regions. They grow at depths of 50 to 75 ft (15–23 m). The red seaweeds (division Rhodophyta), many of them delicate and fernlike, are found at the greatest depths (up to 879 ft/268 m); their red pigment enables them to absorb the blue and violet light present at those depths.
Reproduction in Seaweeds
Seaweeds reproduce in a variety of ways. Lower types reproduce asexually. More advanced kinds produce motile zoospores that swim off, anchor themselves, and grow into new individuals, or they reproduce sexually by forming sex cells (gametes) that, after fusing, follow the same pattern. Sometimes pieces of a seaweed break off and form new plants; in a few species there is a cycle of asexual and sexual reproduction foreshadowing the alternation of generations characteristic of plants.
Common Species and Their Uses
The largest of the green algae, Ulva (sea lettuce), grows to a ribbon or sheet 3 ft (91 cm) long. It provides food for many sea creatures, and its broad surface releases a large amount of oxygen. Fucus, called rockweed or bladderwrack, is a tough, leathery brown alga (though it often looks olive-green) that clings to rocks and has flattened, branched fronds buoyed by air bladders at the tips.
Seaweeds, especially species of the red algae Porphyra (nori) and Chondrus, form an important part of the diet and are farmed for food in China and Japan; other species (often called laver) are eaten in the British Isles and Iceland. Commercial agar (vegetable gelatin) is obtained from species of red algae and is the most valuable seaweed product. Irish moss or carrageen (Chondrus crispus), a red alga, is one of the few seaweeds used commercially in the United States. After being bleached in the sun the fronds contain a high proportion of gelatin, which is used for cooking, textile sizing, making cosmetics, and other purposes. In Japan it is made into a shampoo to impart gloss to the hair.
The kelps generally include the many large brown seaweeds and are among the most familiar forms found on North American coasts. Some have fronds up to 200 ft (61 m) long, e.g., the Pacific coast Nereocystis and Macrocystis, found also off the Cape of Good Hope. Common Atlantic species include Laminaria and Agarum (devil's apron). The kelps are a source of salts of iodine and potassium and, to a lesser extent, other minerals. When the seaweed is burned, the soluble mineral compounds are removed from the ashes (also called kelp) by washing. They are used chiefly as chemical reagents and for dietary deficiencies in people and in livestock. Kelp is also a commercial source of potash, fertilizer, and medicines made from its vitamin and mineral content. Kelps are especially abundant in Japan, and various foods known as kombu are made from them.
The brown algae of the genus Sargassum are called gulfweed. They inhabit warm ocean regions and are commonly found floating in large patches in the Sargasso Sea and in the Gulf Stream. Gulfweed was observed by Columbus. Although it was formerly thought to cover the whole Sargasso Sea, making navigation impossible, it has since been found to occur only in drifts. Numerous berrylike air sacs keep the branching plant afloat. The thick masses of gulfweed provide the environment for a distinctive and specialized group of marine forms, many of which are not found elsewhere.
| Veterinary Dictionary: seaweed |
Sea plants harvested for livestock feed; claimed to be a rich source of minerals and vitamins. When fed to laying hens may discolor yolks.
| Nutritional Values: The Nutritional Value for: seaweed |
| Description | Quantity | Energy (calories) |
Carbs (grams) |
Protein (grams) |
Cholesterol (milligrams) |
Weight (grams) |
Fat (grams) |
Saturated Fat (grams) |
| kelp, raw | 1 oz | 10 | 3 | 0 | 0 | 28.35 | 0 | 0.1 |
| spirulina, dried | 1 oz | 80 | 7 | 16 | 0 | 28.35 | 2 | 0.8 |
| Gardener's Dictionary: seaweed |
Any of various marine algae or plants. Seaweed makes an excellent high-potash fertilizer.
| Word Tutor: seaweed |
Love is like seaweed; even if you have pushed it away, you will not prevent its coming back.
— Nigerian proverb.
| Wikipedia: Seaweed |
| Seaweed | ||
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Ascophyllum nodosum exposed to the sun in Nova Scotia, Canada.
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Seaweed is a loose colloquial term encompassing macroscopic, multicellular, benthic marine algae.[1] The term includes some members of the red, brown and green algae. Seaweeds can also be classified by use (as food, medicine, fertilizer, industrial, etc.).
Contents |
A seaweed may belong to one of several groups of multicellular algae: the red algae, green algae, and brown algae. As these three groups are not thought to have a common multicellular ancestor, the seaweeds are a paraphyletic group. In addition, some tuft-forming bluegreen algae (Cyanobacteria) are sometimes considered as seaweeds—"seaweed" is a colloquial term and lacks a formal definition.
Seaweeds' appearance somewhat resembles non-arboreal terrestrial plants.
The stipe and blade are collectively known as the frond.
The ecology of seaweeds is dominated by two specific environmental requirements. These are the presence of seawater (or at least brackish water) and the presence of light sufficient to drive photosynthesis. A very common requirement is also to have a firm point of attachment. As a result, seaweeds are most commonly found in the littoral zone and within that zone more frequently on rocky shores than on sand or shingle. The ecological niches utilised by seaweeds are wide ranging. At the highest level are those that inhabit the zone that is only wetted by the tops of sea spray, the deepest living are those that are attached to the seabed under several meters of water. In some parts of the world, the area colonized by littoral seaweeds can extend for several miles away from the shore. The limiting factor in such cases is the availability of sufficient sun-light to support photosynthesis. The deepest living seaweeds are the various kelps. In addition to the familiar seashore seaweeds, a number of species have adapted to a fully planktonic niche and are free-floating, often with the assistance of gas filled sacs. Sargassum is one of the better known examples of this type of seaweed.
A number of species have adapted to the specialised environment of tidal rock pools. In this niche seaweeds are able to withstand rapidly changing temperature and salinity and even occasional drying.[2]
Seaweed has a variety of purposes, for which it is farmed,[3] or foraged from the wild.[4]
See also Edible seaweed.
Seaweeds are extensively used as food by coastal people, particularly in East Asia, e.g. Japan, China, Korea, Taiwan, Thailand, and Vietnam, but also in Indonesia, Belize, Peru, the Canadian Maritimes, Scandinavia, Ireland, Wales, Philippines, and Scotland, among other places. Tiwi, Albay residents discovered a new pancit or noodles made from seaweed, which has health benefits. It is rich in calcium and magnesium and the seaweed noodles can be cooked into pancit canton, pancit luglug, spaghetti or carbonara.[5]
In Asia, Zicai (紫菜) (in China), gim (in Korea) and nori (in Japan) are sheets of dried Porphyra used in soups or to wrap sushi. Chondrus crispus (commonly known as Irish moss or carrageenan moss) is another red alga used in producing various food additives, along with Kappaphycus and various gigartinoid seaweeds. Porphyra is a red alga used in Wales to make laver. Laverbread, made from oats and the laver, is a popular dish in Wales. Affectionately called "Dulce" in northern Belize, seaweeds are mixed uniquely with milk, nutmeg, cinnamon, and vanilla to be served as a common beverage throughout the country.
Seaweeds are also harvested or cultivated for the extraction of alginate, agar and carrageenan, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance, especially in food production as food additives.[6] The food industry exploits the gelling, water-retention, emulsifying and other physical properties of these hydrocolloids. Agar is used in foods such as confectionery, meats and poultry products, desserts and beverages and moulded foods. Carrageenan is used in preparation of salad dressings and sauces, dietetic foods, and as a preservative in meat and fish products, dairy items and baked goods. Alginates enjoy many of the same uses as carrageenan, but are also used in production of industrial products such as paper coatings, adhesives, dyes, gels, explosives and in processes such as paper sizing, textile printing, hydro-mulching and drilling.
In the biomedicine and pharmaceutical industries, alginates are used in wound dressings, and production of dental moulds and have a host of other applications. In microbiology research, agar is extensively used as culture medium. Carrageenans, alginates and agaroses (the latter are prepared from agar by purification), together with other lesser-known macroalgal polysaccharides, also have several important biological activities or applications in biomedicine.[citation needed] Seaweed is also a known source of iodine,[7] an element necessary for thyroid function with deficiencies leading to goitre. It has been asserted that seaweeds may have curative properties for tuberculosis, arthritis, colds and influenza, worm infestations and even tumors.[1][dubious ] A number of research studies have been conducted to investigate these claims and other effects of seaweed on human health.[citation needed]
Some studies have found that seaweed can promote weight loss[8][9]. For this reason, seaweed extract is used in some diet pills.[10] Other seaweed pills work similar to gastric banding, they will expand in the stomach to make the body feel more full. [11][12]
Other seaweeds may be used as seaweed fertilizer.[citation needed] Seaweed is currently being researched as a potential source of biofuel in the form of bioethanol.[13][14] Seaweed is also an ingredient in some toothpaste, cosmetics and paints.[3]
This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)
| Translations: Seaweed |
Dansk (Danish)
n. - tang, alger
Français (French)
n. - algue marine
Ελληνική (Greek)
n. - φύκος, φύκια
Português (Portuguese)
n. - alga marinha (f) (Bot.)
Русский (Russian)
морская водоросль
Español (Spanish)
n. - alga marina, algas
Svenska (Swedish)
n. - sjögräs, alger
中文(简体)(Chinese (Simplified))
海草, 海藻
中文(繁體)(Chinese (Traditional))
n. - 海草, 海藻
العربيه (Arabic)
(الاسم) ألعشب ألبحري
עברית (Hebrew)
n. - אצה, אצת-ים
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