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Information about Seaweed

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Ascophyllum nodosum exposed to the sun in Nova Scotia, Canada
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Dead Man's Fingers (Codium fragile) off Massachusetts coast


For the band, see; Seaweed (band)
For the rock musician, see; Seaweed (musician)
Seaweeds are any of a large number of marine benthic algae. They are macroscopic and multicellular, in contrast with most other algae. [1] Seaweeds areoften found in the seashore biome.

Taxonomy

Seaweeds consist 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, tuft-forming bluegreen algae (Cyanobacteria) are sometimes considered as seaweeds.

Seaweeds are popularly described as plants, but only red and green algae belong to the kingdom Plantae). They should not be confused with aquatic plants such as seagrasses (which are vascular plants).

Structure

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The top of a kelp forest in Otago, New Zealand
Seaweeds' appearance somewhat resembles non-arboreal terrestrial plants.
  • thallus: the algal body
  • lamina: a flattened structure that is somewhat leaf-like
  • sorus: spore cluster
  • on Fucus, air bladders: float-assist organ (on blade)
  • on kelp, floats: float-assist organ (between lamina and stipe)
  • stipe: a stem-like structure, may be absent
  • holdfast: specialized basal structure providing attachment to a surface, often a rock or another alga.
The stipe and blade are collectively known as fronds.

Ecology

The ecology of seaweeds is dominated by two specific environmental requirements. These are the presence of sea-water (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 sea-bed 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 sea-weeds are the various kelps.

In addition to the familiar sea-shore 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 know 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]

Uses

Food

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Packaged seaweed
Seaweeds are extensively used as food by coastal peoples, particularly in East Asia, e.g. Japan, China, Korea, Taiwan, and Vietnam, but also in Indonesia, Peru, the Canadian Maritimes, Scandinavia, Ireland, Wales, Philippines, and Scotland, among other places. For example, Porphyra is a red alga used in Wales to make laverbread. In Asia, nori is a food composed of sheets of dried Porphyra and is 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. Laverbread made from oats and the seaweed laver is a popular dish in Wales.

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. [3] 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 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. It has been asserted that seaweeds may have curative properties for tuberculosis, arthritis, colds and influenza, worm infestations and even tumors [1]. A number of research studies have been conducted to investigate these claims and other effects of seaweed on human health [2].

See also Fucoidan

Other uses

Other seaweeds may be used as seaweed fertilizer.

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Seaweed-covered rocks in the UK

References

1. ^ Smith, G.M. 1944. Marine Algae of the Monterey Peninsula, California. Stanford Univ., 2nd Edition.
2. ^ Lewis, J.R. 1964. The Ecology of Rocky Shores. The English Universities Press Ltd.
3. ^ Round F.E. 1962 The Biology of the Algae. Edward Arnold Ltd.

External links

Seaweed is a band from Tacoma, Washington who were active throughout the 1990s. Their style of music is a combination of punk rock and grunge, mostly due to its 'dirty' sound.
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Seaweed is a rock musician from North Carolina, United States. He was a longtime feature in the cult punk band Frankenstein Drag Queens From Planet 13 with Wednesday 13. Seaweed went on to play in another horror punk band The Graveyard Boulevard in which he was the vocalist and
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Earth's oceans
(World Ocean)
  • Arctic Ocean
  • Atlantic Ocean
  • Indian Ocean
  • Pacific Ocean
  • Southern Ocean
An ocean (from Ωκεανός, Okeanos
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Benthos are the organisms which live on, in, or near the seabed, also known as the benthic zone.[1] Although the term derived from the Greek for "depths of the sea"<ref name="caml" />, the term is also used in freshwater biology to refer to organisms at
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phytoplankton — provide the food base for most marine food chains. In very high densities (so-called algal blooms) these algae may discolor the water and outcompete or poison other life forms.
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Multicellular organisms are organisms consisting of more than one cell, and having differentiated cells that perform specialized functions. Most life that can be seen with the naked eye is multicellular, as are all members of the kingdoms Plantae and Animalia (except for
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A biome is a major geographical area of ecologically similar communities of plants, animals, and soil organisms, often referred to as ecosystems. Biomes are defined based on factors such as plant structures (such as trees, shrubs, and grasses), leaf types (such as broadleaf and
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phytoplankton — provide the food base for most marine food chains. In very high densities (so-called algal blooms) these algae may discolor the water and outcompete or poison other life forms.
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Rhodophyta
Wettstein, 1922

Possible classes
  • Florideophyceae
  • Bangiophyceae
  • Cyanidiophyceae
The red algae (Rhodophyta, IPA:
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Green algae are microscopic protists; found in all aquatic environments, including marine, freshwater and brackish water.

The green algae (singular: green alga) are the large group of algae from which the embryophytes (higher plants) emerged.
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Phaeophyceae
Kjellman

The Phaeophyceae or brown algae, (singular: alga) is a large group of mostly marine multicellular algae, including many seaweeds of colder Northern Hemisphere waters.
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In phylogenetics, a group of organisms is said to be paraphyletic (Greek para = near and phyle = race) if the group contains its most recent common ancestor, but does not contain all the descendants of that ancestor.
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kingdom or regnum is a taxon in either (historically) the highest rank, or (in the new three-domain system) the rank below domain. Each kingdom is divided into smaller groups called phyla (or in some contexts these are called "divisions").
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Plantae
Haeckel, 1866[1]

Divisions

Green algae
  • Chlorophyta
  • Charophyta
Land plants (embryophytes)
  • Non-vascular land plants (bryophytes)

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This article or section needs copy editing for grammar, style, cohesion, tone and/or spelling.
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This article has been tagged since September 2007.
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Divisions
  • Non-seed-bearing plants
  • †Rhyniophyta
  • †Zosterophyllophyta
  • Lycopodiophyta

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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 bushes.
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Plantae
Haeckel, 1866[1]

Divisions

Green algae
  • Chlorophyta
  • Charophyta
Land plants (embryophytes)
  • Non-vascular land plants (bryophytes)

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Thallus, from Latinized Greek θαλλος (thallos), meaning a green shoot or twig, is an undifferentiated vegetative tissue of some non-mobile organisms, which were previously known as the thallophytes.
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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.
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sorus (pl. sori) is a cluster of sporangia on the edge or underside of a fertile frond. In many species, they are protected by an umbrella-like cover called the indusium.
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spore is a reproductive structure that is adapted for dispersion and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many plants, algae, fungi and some protozoans.
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Fucus
L.

Species
See text

Fucus is a genus of brown alga (seaweed) in the Class Phaeophyceae to be found in the intertidal zones of rocky shores. It is a common genus found on the Atlantic coasts of Europe and North America.
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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.
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Laminariales
Migula

Families

Alariaceae
Chordaceae
Laminariaceae
Lessoniaceae
Phyllariaceae
Pseudochordaceae

Kelp are large seaweeds (algae), belonging to the brown algae and classified in the order Laminariales.
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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.
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In botany, a stipe is a supportive structure that may be the stem-like part of the thallus of a seaweed or a true leaf stem, as in ferns.

In the case of ferns, the stipe is only the petiole (or stem) from the rootstock to the beginning of the leaf tissue, or lamina.
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holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, colonial cnidarians, and sponges, to the substrate [1].
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frond is a large leaf with many divisions to it, and the term is typically used for the leaves of palms, ferns or cycads. [1]

A frond is the leaf- like structure of a fern or alga.
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Brackish water (less commonly brack water) is water that is saltier than fresh water, but not as salty as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers.
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