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Seaweed is a loose colloquial term encompassing macroscopic, multicellular, benthic
Benthos

Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the Intertidal zone, out to the continental shelf, and then down to the Abyssal zone....
 marine
Ocean

An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas....
 algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
. 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.).

aweed may belong to one of several groups of multicellular algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
: the red algae, green algae, and brown algae.






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Kelp Forest Otago 1s
Seaweed is a loose colloquial term encompassing macroscopic, multicellular, benthic
Benthos

Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone. They live in or near marine sedimentary environments, from tidal pools along the Intertidal zone, out to the continental shelf, and then down to the Abyssal zone....
 marine
Ocean

An ocean is a major body of Seawater, and a principal component of the hydrosphere. Approximately 71% of the Earth's surface is covered by ocean, a World Ocean that is customarily divided into several principal oceans and smaller seas....
 algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
. 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.).

Taxonomy

A seaweed may belong to one of several groups of multicellular algae
Algae

Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms. The largest and most complex marine forms are called seaweeds....
: 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
Paraphyly

In phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor Common descent but does not contain all the descendants of that ancestor....
 group. In addition, some tuft-forming bluegreen algae (Cyanobacteria
Cyanobacteria

Cyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis....
) are sometimes considered as seaweeds—"seaweed" is a colloquial term and lacks a formal definition.

Structure

Seaweeds' appearance somewhat resembles non-arboreal
Arboreal

Arboreal is a word meaning "related to or resembling trees". Its meaning comes from the Latin arbor, meaning tree.In biology, an arboreal animal is one which inhabits or spends large amounts of time in trees or Shrubes....
 terrestrial plant
Plant

Plants are Life organisms belonging to the Kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae....
s.
  • thallus
    Thallus (tissue)

    File:Sargassum weeds closeup.jpgThallus, from Latinized Greek language ?a???? , meaning a green shoot or twig, is an cellular differentiation vegetative tissue of some non-mobile organisms, which were previously known as the thallophytes....
    : the algal body
    • lamina
      Lamina (algae)

      A Lamina in the algae is a generally flattened structure which typically forms the principal bulk of macroscopic plants. It is often developed into specialised organs such as flotation bladders and reproductive organs....
      : a flattened structure that is somewhat leaf-like
      • sorus
        Sorus

        A sorus is a cluster of sporangium.In fungi and lichens, the sorus is surrounded by an external layer. In some red algae it may take the form of a depression into the thallus....
        : spore
        Spore

        In biology, a spore is a reproduction structure that is adapted for biological dispersal and surviving for extended periods of time in unfavorable conditions....
         cluster
      • on Fucus
        Fucus

        Fucus is a genus of brown alga in the Class Phaeophyceae to be found in the intertidal zones of rocky shores. It is a common genus found on the Atlantic Ocean coasts of Europe and North America....
        , air bladders: float
        Pneumatocyst

        In phytology, a pneumatocyst is a large float containing gas found in brown algae. An organism may have more than one. They provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for photosynthesis....
        -assist organ (on blade)
      • on kelp
        Kelp

        Kelp are large seaweed plants , belonging to the brown algae and classified in the order Laminariales. There are about 30 different genus. Some species can be very long and form kelp forests....
        , float
        Pneumatocyst

        In phytology, a pneumatocyst is a large float containing gas found in brown algae. An organism may have more than one. They provide buoyancy to lift the blades toward the surface, allowing them to receive more sunlight for photosynthesis....
        s: float-assist organ (between lamina and stipe)
    • stipe
      Stipe (botany)

      In botany, a stipe is a stalk that supports some other structure. The precise meaning is different depending on which taxonomic group is being described....
      : a stem-like structure, may be absent
    • holdfast
      Holdfast

      A holdfast is a root-like structure that anchors aquatic animal Sessility organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. ...
      : specialized basal structure providing attachment to a surface, often a rock or another alga.
    • haptera: finger-like extensions of holdfast anchoring to benthic substrate
The stipe and blade are collectively known as the frond
Frond

A frond is a large leaf with many divisions to it, and the term is typically used for the leaves of Arecaceaes, ferns or cycads. A frond is the leaf- like structure of a fern or alga....
.

Ecology
Ecology

Ecology is the science study of the distribution and Abundance of life and the interactions between organisms and their nature environment ....

The ecology of seaweeds is dominated by two specific environmental requirements. These are the presence of seawater (or at least brackish water
Brackish water

Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuary, or it may occur in brackish fossil aquifers....
) and the presence of light sufficient to drive photosynthesis
Photosynthesis

File:Seawifs global biosphere.jpgPhotosynthesis is a metabolic pathway that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight....
. A very common requirement is also to have a firm point of attachment. As a result, seaweeds are most commonly found in the littoral
Littoral

In coastal environments and biomes, the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged....
 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 kelp
Kelp

Kelp are large seaweed plants , belonging to the brown algae and classified in the order Laminariales. There are about 30 different genus. Some species can be very long and form kelp forests....
s. 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
Sargassum

Sargassum is a genus of generally planktonic macroalgae in the order Fucales. It is named for the Atlantic Ocean's Sargasso Sea, which hosts a large amount of several species of 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.

Uses

Seaweed has a variety of purposes, for which it is farmed
Agriculture

Agriculture refers to the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of civilization, with the animal husbandry of domestication animals and plants creating food surpluses that enabled the development of more Population density and Social stratification societies....
, or foraged from the wild.

Food

Seaweeds are extensively used as food by coastal people, particularly in East Asia, e.g. Japan
Japan

Japan is an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south....
, China
China

China is a Culture of China, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
, Korea
Korea

Korea is a geographic area composed of two sovereign countries, a civilization, and a former state situated on the Korean Peninsula in East Asia....
, Taiwan
Taiwan

Taiwan is an island in East Asia. "Taiwan" is also commonly used to refer to the country governed by the Republic of China and to the ROC itself, which governs the island of Taiwan, Orchid Island and Green Island, Taiwan in the Pacific Ocean off the Taiwan coast, the Penghu islands in the Taiwan Strait, and Kinmen and the Matsu Islands...
, and Vietnam
Vietnam

Vietnam , officially the Socialist Republic of Vietnam , is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by People's Republic of China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea to the east....
, but also in Indonesia
Indonesia

The Republic of Indonesia , is a transcontinental country in Southeast Asia and Oceania. Comprising Islands of Indonesia, it is the world's largest Archipelago state....
, Peru
Peru

Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
, the Canadian Maritimes, Scandinavia
Scandinavia

Scandinavia is a historical and geographical subregion in northern Europe that includes the Scandinavian Peninsula. It consists of the kingdoms of Norway, Sweden, and Denmark; some authorities also include Finland and some might even include Iceland....
, Ireland
Ireland

Ireland is the List of islands by area in Europe, and the twentieth-largest island in the world. It lies to the north-west of continental Europe and is surrounded by hundreds of islands and islet....
, Wales
Wales

native_name = Cymru|conventional_long_name = Wales|common_name = Wales|image_flag = Flag of Wales 2.svg|national_motto = ...
, Philippines
Philippines

The Philippines, officially known as the Republic of the Philippines, is a country in Southeast Asia with Manila as its capital city. It comprises 7,107 islands in the western Pacific Ocean....
, and Scotland
Scotland

conventional_long_name = ScotlandAlba|common_name= Scotland|image_flag = Flag of Scotland.svg|flag_width = 130px...
, among other places. Tiwi
Tiwi

Tiwi can refer to:*Tiwi, Albay, a municipality in the province of Albay, Philippines*Tiwi, Northern Territory, a suburb of Darwin, Northern Territory, Northern Territory, Australia...
, Albay
Albay

Albay calcium
Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
 and magnesium
Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, atomic weight 24.3050 and common oxidation number +2.Magnesium, an alkaline earth metal, is the ninth most abundance of the chemical elements in the universe by mass....
 and the seaweed noodles can be cooked into pansit canton, pansit luglug, spaghetti
Spaghetti

Spaghetti is a long, thin, cylindrical pasta of Italy origin. A variety of pasta dishes are based on it, from spaghetti with cheese and pepper or garlic and oil to a spaghetti with tomato, meat, and other sauces....
 or carbonara
Carbonara

Pasta alla carbonara is an Italy pasta dish based on Egg s, pecorino romano, guanciale, and black pepper. It was invented in the middle of the 20th century....
.

In Asia, Zicai ?? (in China), gim (in Korea) and nori
Nori

is the Japanese name for various edible seaweed species of the red alga Porphyra including most notably P. yezoensis and P. tenera, sometimes called laver ....
 (in Japan) are sheets of dried Porphyra
Porphyra

Porphyra is a foliose red algal genus of Laver , comprising approximately 70 species. It grows in the intertidal, typically between the upper intertidal to the splash zone....
 used in soups or to wrap sushi
Sushi

In Japanese cuisine, is vinegared rice, usually topped with other ingredients, including fish dishes. In Japan, sliced raw fish alone is called sashimi and is distinct from sushi, as sashimi is the raw fish component, not the rice component....
. Chondrus crispus (commonly known as Irish moss
Irish moss

Chondrus crispus, known under the common name Irish moss, or carrageen moss , is a species of red alga which grows abundantly along the rocky parts of the Atlantic Ocean coast of Europe and North America....
 or carrageenan
Carrageenan

Carrageenans or carrageenins are a family of linear sulphated polysaccharides extracted from red seaweeds. The name is derived from a type of seaweed that is abundant along the Ireland coastline....
 moss) is another red alga used in producing various food additives, along with Kappaphycus
Kappaphycus

Kappaphycus is a genus of thalloid alga comprising approximately 6 species. Its members are known by a number of common names.Recorded common names are tambalang, adik goma, vanguard giant, tambalang putan, adik kalas, tambalang milo, tambalang green, purdoy, sacol green, bohol, kab kab and cottonii. Specimens can r...
 and various gigartinoid seaweeds. Porphyra is a red alga used in Wales to make laver
Laver (seaweed)

Laver is an Eating seaweed that has a high mineral salt content, particularly iodine and iron. It is used for making #Laverbread, a traditional Welsh dish....
. Laverbread
Laverbread

#REDIRECT Laver #Laverbread...
, made from oats and the laver, is a popular dish in Wales.

Seaweeds are also harvested or cultivated for the extraction of alginate, agar
Agar

Agar or agar agar is a gelatinous substance derived from seaweed. Historically and in a modern context, it is chiefly used as an ingredient in desserts throughout Japan, but in the past century has found extensive use as a solid substrate to contain Growth medium for microbiology work....
 and carrageenan
Carrageenan

Carrageenans or carrageenins are a family of linear sulphated polysaccharides extracted from red seaweeds. The name is derived from a type of seaweed that is abundant along the Ireland coastline....
, gelatinous substances collectively known as hydrocolloids or phycocolloids. Hydrocolloids have attained commercial significance, especially in food production as food additives. 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.

Medicine

Seaweed 600
:See also Fucoidan
Fucoidan

Fucoidan is a sulfated polysaccharide found mainly in various species of brown seaweed such as kombu, limu moui, bladderwrack, wakame, mozuku, and hijiki ....
 In the biomedicine
Biomedicine

Biomedicine, also known as theoretical medicine, is a term that comprises the knowledge and research which is more or less in common to the fields of medicine, veterinary medicine, odontology and fundamental biosciences such as biochemistry, chemistry, biology, cell biology, genetics, embryology, anatomy, physiology, pathology, biomedical...
 and pharmaceutical industries, alginates are used in wound dressings, and production of dental moulds and have a host of other applications. In microbiology
Microbiology

Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryote such as fungi and protists, and prokaryotes, which are bacteria and archaea....
 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. Seaweed is also a known source of iodine
Iodine

Iodine , is a chemical element that has the symbol I and atomic number 53. Naturally-occurring iodine is a single isotope with 74 neutrons....
, an element necessary for thyroid
Thyroid

The thyroid is one of the largest endocrine glands in the body. This gland is found in the neck inferior to the thyroid cartilage and at approximately the same level as the cricoid cartilage....
 function with deficiencies leading to goitre
Goitre

A goitre , or goiter , also called a bronchocele, is a swelling in the neck due to an enlarged thyroid....
. It has been asserted that seaweeds may have curative properties for tuberculosis
Tuberculosis

Tuberculosis is a common and often deadly infectious disease caused by mycobacterium, mainly Mycobacterium tuberculosis . Tuberculosis usually attacks the lungs but can also affect the central nervous system, the lymphatic system, the circulatory system, the genitourinary system, the gastrointestinal system, bones, joints, and even the...
, arthritis
Arthritis

Arthritis is a group of conditions involving damage to the joints of the body. Arthritis is the leading cause of disability in people older than fifty-five years....
, colds and influenza
Influenza

Influenza, commonly known as the flu, is an infectious disease that affects birds and mammals caused by RNA viruses of the biological family Orthomyxoviridae ....
, worm infestations and even tumors. A number of research studies have been conducted to investigate these claims and other effects of seaweed on human health.

Some studies have found that seaweed can promote weight loss. For this reason, seaweed extract is used in some diet pills. Other seaweed pills work similar to gastric banding, they will expand in the stomach to make the body feel more full.

Other uses

Other seaweeds may be used as seaweed fertilizer. Seaweed is currently being researched as a potential source of biofuel
Biofuel

Biofuel is defined as solid, liquid or gaseous fuel derived from relatively recently dead biological material and is distinguished from fossil fuels, which are petroleum#formation....
 in the form of bioethanol. Seaweed is also an ingredient in some toothpaste, cosmetics and paints.

See also


External links

  • , information on all aspects of seaweeds and marine algal biology
  • , a searchable taxonomic, image, and utilization database of freshwater, marine and terrestrial algae, including seaweed.
  • , information on seaweed utilisation for the African continent.