SeaweedSeaweed has antioxidents. Is a loose colloquial term encompassing macroscopic, multicellular,
benthicBenthos 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 foreshore, out to the continental shelf, and then down to the abyssal depths....
marineAn ocean is a large body of saline water, and a principal component of the hydrosphere. Approximately 75% of the Earth's surface is covered by ocean, a continuous body of water that is customarily divided into several principal oceans and smaller seas.More than half of this area is over 3,000...
algaeAlgae 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. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
. 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
algaeAlgae 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. They are photosynthetic, like plants, and "simple" because they lack the many distinct organs found in...
: 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
paraphyleticIn phylogenetics, a group of organisms is said to be paraphyletic if the group contains its most recent common ancestor but does not contain all the descendants of that ancestor.- Relation to monophyletic groups :...
group. In addition, some tuft-forming bluegreen algae (
CyanobacteriaCyanobacteria, also known as blue-green algae, blue-green bacteria or Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis. The name "cyanobacteria" comes from the color of the bacteria = blue)...
) are sometimes considered as seaweeds — "seaweed" is a colloquial term and lacks a formal definition.
Structure
Seaweeds' appearance somewhat resembles non-arboreal terrestrial
plantPlants are living organisms belonging to the kingdom Plantae. They include familiar organisms such as trees, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The scientific study of plants, known as botany, has identified about 350,000 extant species of plants, defined as seed plants,...
s.
- thallus
Thallus, from Latinized Greek θαλλός , meaning a green shoot or twig, is an undifferentiated vegetative tissue of some non-mobile organisms, which were previously known as the thallophytes....
: the algal body
- lamina
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
A sorus is a cluster of sporangia.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....
: sporeIn biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions...
cluster
- on Fucus
Fucus is a genus of brown alga in the Class Phaeophyceae to be found in the intertidal zones of rocky seashores almost everywhere in the world.-Description and life cycle:...
, air bladders: floatIn 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
{Taxobox| name =Kelp| image = Kelp In Freycinet Tasmania.jpg| image_width = 300px| image_caption = Kelp on rocky beach in Freycinet, Tasmania| regnum = Chromalveolata| phylum = Heterokontophyta| classis = Phaeophyceae| ordo = Laminariales...
, floatIn 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
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
A holdfast is a root-like structure that anchors aquatic sessile 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
frondThe term frond is used to refer to a large, divided leaf.In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group...
.
Ecology
The
ecologyEcology is the interdisciplinary scientific study of the interactions between organisms and the interactions of these organisms with their environment....
of seaweeds is dominated by two specific environmental requirements. These are the presence of seawater (or at least
brackish waterBrackish 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 estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salten" or "salty"...
) and the presence of light sufficient to drive
photosynthesisPhotosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea...
. A very common requirement is also to have a firm point of attachment. As a result, seaweeds are most commonly found in the
littoralIn coastal environments and biomes, the littoral zone extends from the high water mark, which is rarely inundated, to shoreline areas that are permanently submerged. It always includes the intertidal zone and is often used to mean the same as the intertidal zone...
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{Taxobox| name =Kelp| image = Kelp In Freycinet Tasmania.jpg| image_width = 300px| image_caption = Kelp on rocky beach in Freycinet, Tasmania| regnum = Chromalveolata| phylum = Heterokontophyta| classis = Phaeophyceae| ordo = Laminariales...
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.
SargassumSargassum is a genus of brown macroalga in the order Fucales. Numerous species are distributed throughout the temperate and tropical oceans of the world, where they generally inhabit shallow water and coral reefs. However, the genus may be best known for its planktonic species...
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
farmedAgriculture is the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and...
, or foraged from the wild.
Food
Seaweeds are extensively used as food by coastal people, particularly in East Asia, e.g.
Japanis 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...
,
ChinaChina is a cultural region, an ancient civilization, and, depending on perspective, a national or multinational entity extending over a large area in East Asia....
,
KoreaKorea is a civilization and formerly unified nation currently divided into two states. Located on the Korean Peninsula, it borders China to the northwest, Russia to the northeast, and is separated from Japan to the east by the Korea Strait....
,
TaiwanTaiwan , also known as Formosa , is the largest island of the Republic of China in East Asia. Taiwan is located east of the Taiwan Strait, off the southeastern coast of mainland China...
,
ThailandThe Kingdom of Thailand is an independent country that lies in the heart of Southeast Asia.It is bordered to the north by Laos and Burma, to the east by Laos and Cambodia, to the south by the Gulf of Thailand and Malaysia, and to the west by the Andaman Sea and Burma...
, and
VietnamVietnam , officially the Socialist Republic of Vietnam , is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea to the east...
, but also in
IndonesiaThe Republic of Indonesia is a country in Southeast Asia and Oceania. Indonesia comprises 17,508 islands. With an estimated population of around 237 million people, it is the world's fourth most populous country, with the world's largest population of Muslims.Indonesia is a republic, with an...
,
BelizeBelize , is a country in Central America. Belize has a diverse society, composed of many cultures and speaking many languages. Although Kriol and Spanish are spoken among the population, Belize is the only country in Central America where English is the official language...
,
PeruPeru , 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.Peruvian territory was home to the Norte Chico...
, the Canadian Maritimes,
ScandinaviaScandinavia is a geographical region in northern Europe that includes, and is named after, the Scanian Province. It consists of the kingdoms of Norway, Sweden, and Denmark...
,
IrelandIreland is the third-largest island 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 islets. To the east of Ireland, separated by the Irish Sea, is the island of Great Britain...
,
WalesWales is a country that is part of the United Kingdom, bordered by England to its east, and the Atlantic Ocean and Irish Sea to its west. It is also an elective region of the European Union...
,
PhilippinesThe 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
ScotlandScotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
, among other places.
TiwiTiwi can refer to:*Tiwi, Albay, a municipality in the province of Albay, Philippines*Tiwi, Kenya, a settlement in Kenya's Coast Province*Tiwi, Northern Territory, a suburb of Darwin in Australia*The Tiwi Islands, 80km north of Darwin...
,
AlbayAlbay is a province of the Philippines located in the Bicol Region in Luzon. Its capital is Legazpi City and the province borders Camarines Sur to the north and Sorsogon to the south...
residents discovered a new
pancitPancit or '"Pansit"' is a noodle dish common in the Philippines of Chinese origin and is similar to yakisoba and yakiudon, Japanese-style stir-fried noodles.-Variations:*Pancit Alanganin**Pancit Cabagan...
or noodles made from seaweed, which has health benefits. It is rich in
calciumCalcium 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
magnesiumMagnesium is a chemical element with the symbol Mg, atomic number 12 and common oxidation number +2. It is an alkaline earth metal and the eighth most abundant element in the earth's crust by mass, although ninth in the Universe as a whole...
and the seaweed noodles can be cooked into pancit canton, pancit luglug,
spaghettiSpaghetti is a long, thin, cylindrical pasta of Italian 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
carbonaraPasta alla carbonara is an Italian pasta dish based on eggs, pecorino romano, guanciale, and black pepper...
.
In Asia, Zicai (紫菜) (in China), gim (in Korea) and
noriis the Japanese name for various edible seaweed species of the red alga Porphyra including most notably P. yezoensis and P. tenera, sometimes called laver . The term nori is also commonly used to refer to the food products created from these "sea vegetables", similar to the Korean gim...
(in Japan) are sheets of dried
PorphyraPorphyra is a foliose red algal genus of laver, comprising approximately 70 species. It grows in the intertidal zone, typically between the upper intertidal zone and the splash zone in cold waters of temperate oceans. In East Asia, it is used to produce the sea vegetable products nori and gim ,...
used in soups or to wrap
sushiIn Japanese cuisine, ' is vinegar rice, usually topped with other ingredients, such as fish. In spelling sushi its first letter s is replaced with z when a prefix is attached, as in nigirizushi, due to consonant mutation called rendaku in Japanese.Sliced raw fish alone is called sashimi, as...
.
Chondrus crispus (commonly known as
Irish mossChondrus 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 coast of Europe and North America...
or
carrageenanCarrageenans or carrageenins are a family of linear sulphated polysaccharides extracted from red seaweeds.The origin of the name is unclear and references to a county in Ireland are common but false. It is most likely to derive from an Irish language phrase for "little rock"...
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
laverLaver is an edible seaweed that has a high mineral salt content, particularly iodine and iron. It is used for making laverbread, a traditional Welsh dish. Laver is common around the west coast of Britain and east coast of Ireland along the Irish Sea. Laver is unique among seaweeds because it is...
. 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,
agarAgar 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 culture medium for microbiological work...
and
carrageenanCarrageenans or carrageenins are a family of linear sulphated polysaccharides extracted from red seaweeds.The origin of the name is unclear and references to a county in Ireland are common but false. It is most likely to derive from an Irish language phrase for "little rock"...
, 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
In the
biomedicineBiomedicine, 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 human medicine, veterinary medicine, odontology and fundamental biosciences such as biochemistry, chemistry, biology, histology, genetics,...
and pharmaceutical industries, alginates are used in wound dressings, and production of dental moulds and have a host of other applications. In
microbiologyMicrobiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryotes such as fungi and protists, and prokaryotes. Viruses, though not strictly classed as living organisms, are also studied...
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
iodineIodine , 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
thyroidThe 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
goitreA goitre , or goiter , also called a bronchocele, is a swelling in the thyroid gland, which can lead to a swelling of the neck or larynx...
.
It has been asserted that seaweeds may have curative properties for
tuberculosisTuberculosis is a common and often deadly infectious disease caused by mycobacteria...
,
arthritisArthritis is a group of conditions involving damage to the joints of the body....
, colds and
influenzaInfluenza, commonly referred to as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae , that affects birds and mammals. The name influenza is Italian and means "influence"...
, worm infestations and even tumors.
http://www.seaweed.ie/uses_general/MedicinalUses.html 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
biofuelBiofuel is defined as solid, liquid or gaseous fuel obtained from lifeless or living biological material and is similar to fossil fuels, which are derived from long dead biological material. Also, various plants and plant-derived materials are used for biofuel manufacturing...
in the form of bioethanol. Seaweed is also an ingredient in some toothpaste, cosmetics and paints.
See also
- Algaculture
Algaculture is a form of aquaculture involving the farming of species of algae.The majority of algae that are intentionally cultivated fall into the category of microalgae...
- Algal fuel
- Kelp
{Taxobox| name =Kelp| image = Kelp In Freycinet Tasmania.jpg| image_width = 300px| image_caption = Kelp on rocky beach in Freycinet, Tasmania| regnum = Chromalveolata| phylum = Heterokontophyta| classis = Phaeophyceae| ordo = Laminariales...
- Ogonori
Ogonori , also called ogo or sea moss, is a type of edible seaweed eaten along the coasts of Japan, Southeast Asia, Hawaii, and the Caribbean. Ogonori is typically eaten cold and is a source of the thickener agar.-Uses:...
- Sea lettuce
The sea lettuces comprise the genus Ulva, a group of edible green algae widely distributed along the coasts of the world's oceans....
- Seaweed dermatitis
Seaweed dermatitis is a cutaneous condition characterized by inflammation of the skin caused by marine alga, specifically Lyngbya majuscula....
- Wakame
, Undaria pinnatifida, is a sea vegetable, or edible seaweed, that has been nominated as among 100 of the world's worst invasive species according to the Global Invasive Species Database. In Japan it is most widely used in miso soup.-History in the West:...
Seaweed genera
- Caulerpa
Caulerpa is a genus of seaweeds in the family Caulerpaceae . They are unusual because they consist of only one cell with many nuclei, making them among the biggest single cells in the world...
- Fucus
Fucus is a genus of brown alga in the Class Phaeophyceae to be found in the intertidal zones of rocky seashores almost everywhere in the world.-Description and life cycle:...
- Gracilaria
Gracilaria is a genus of red algae notable for its economic importance as an agarophyte, as well as its use as a food for humans and various species of shellfish...
- Laminaria
Laminaria is a genus of 31 species of brown algae , all sharing the common name "kelp". This economically important genus is characterized by long, leathery laminae and relatively large size. Some species are referred to by the common name Devil's apron, due to their shape, or sea colander, due to...
- Macrocystis
Macrocystis is a genus of kelp . This genus contains the largest of all the phaeophyceae or brown algae. Macrocystis has pneumatocysts at the base of its blades. Sporophytes are perennial, and individual stipes may persist for many years...
- Monostroma
In taxonomy, Monostroma is a genus of algae, specifically of the Monostromataceae.-Scientific databases:* * *...
- Porphyra
Porphyra is a foliose red algal genus of laver, comprising approximately 70 species. It grows in the intertidal zone, typically between the upper intertidal zone and the splash zone in cold waters of temperate oceans. In East Asia, it is used to produce the sea vegetable products nori and gim ,...
External links
- The Seaweed Site, information on all aspects of seaweeds and marine algal biology
- AlgaeBase, a searchable taxonomic, image, and utilization database of freshwater, marine and terrestrial algae, including seaweed.
- SeaweedAfrica, information on seaweed utilisation for the African continent.
- Seaweed Malaysia Site, information on seaweed nutrition, facts and information for human health.