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Brief Summary

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Red seaweeds are a favorite object for scientists to study because they are specialized plants with unusual properties. Polysiphonia is one such seaweed. It consists of long thin branches with lots of fine side branches. When looked at under a microscope, you see its typical complex tube-like structure. Some species are black-brown, others are bright red. Sometimes Polysiphonia forms thick mats, providing a good bottom for other seaweeds to attach to. Other times, it uses seaweeds or rocks for its own base. One species always grows on knotted wrack (see photo), but is rarely found nowadays. Most Polysiphonias grow in the lower tidal zone. They grow just as well in rough as calm and salty as brackish water.
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Polysiphonia

provided by wikipedia EN

Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles[1] and about 200 species worldwide,[2] including Crete in Greece, Antarctica and Greenland.[3][4] Its members are known by a number of common names.[note 1][3] It is in the order Ceramiales and family Rhodomelaceae.[5]

Description

Polysiphonia is a red algae, polysiphonous[1] and usually well branched, with some plants reaching a length of about 30 cm. They are attached by rhizoids or haptera[4] to a rocky surface or other alga. The thallus (tissue) consists of fine branched filaments each with a central axial filament supporting pericentral cells.[6] The number of these pericentral cells (4–24) is used in identification.[7][8][9] Polysiphonia elongata[10] shows a central axial cell with 4 periaxial cells with cortical cells growing over the outside on the older fronds.[1] Its cuticle contains bromine.[11]

Features used in identification include the number of pericentral cells, the cortication of main branches, constriction of young branches at their base, whether the branching dichotomous or spiral, and the width and length of thalli.

Distribution and ecology

Species have been recorded from Europe, Australia and New Zealand, North America and South America, islands in the Pacific Ocean, South Africa, southwest Asia, Japan, Greenland and Antarctica.[3]

The species are entirely marine, found growing on rock, other algae, mussels or limpets and artificial substrata etc. from mid-littoral to at least 27 m depth. Many species are abundant in rock pools.[1] Polysiphonia lanosa is commonly found growing on Ascophyllum nodosum.[12]

Reproduction and life cycle

The life-cycle of the red algae has three stages (triphasic). In Polysiphonia it consists of a sequence of a gametangial, carpospoangial and tetrasporangial phases.[13][14] Male (haploid) plants (the male gametophytes]) produce spermatia and the female plants (the female gametophytes) produce the carpogonium (the haploid carpogonium) which remains attached to the parent female plant. After fertilization the diploid nucleus migrates and fuses with an auxiliary cell. A complex series of fusions and developments follow as the diploid zygote develops to become the carposporophyte, this is a separate phase of the life-cycle and is entirely parasitic on the female, it is surrounded by the haploid pericarp of the parent female plant. The diploid carpospores produced in the carposporangium when released are non-motile, they settle and grow to form filamentous diploid plants similar to the gametophyte. This diploid plant is the tetrasporophyte which when adult produced spores in fours after meiosis. These spores settle and grow to become the male and female plants thus completing the cycle.[7][15]

Species

The species currently recognized are:

Notes

  1. ^ Recorded common names are olann dhearg, craonach, cúnach triosgar, cluaisíní, mileara, millreacha, salata tou yialou (σαλάτα του γιαλού) and lobster horns.

References

  1. ^ a b c d Maggs, C.A. & Hommersand, M.H. (1993). Seaweeds of the British Isles. Volume 1: Rhodophyta. HMSO, London. ISBN 978-0-11-310045-3. OCLC 28928653..mw-parser-output cite.citation{font-style:inherit}.mw-parser-output q{quotes:"""""'"'"}.mw-parser-output code.cs1-code{color:inherit;background:inherit;border:inherit;padding:inherit}.mw-parser-output .cs1-lock-free a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/6/65/Lock-green.svg/9px-Lock-green.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-limited a,.mw-parser-output .cs1-lock-registration a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/d/d6/Lock-gray-alt-2.svg/9px-Lock-gray-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-lock-subscription a{background:url("//upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Lock-red-alt-2.svg/9px-Lock-red-alt-2.svg.png")no-repeat;background-position:right .1em center}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration{color:#555}.mw-parser-output .cs1-subscription span,.mw-parser-output .cs1-registration span{border-bottom:1px dotted;cursor:help}.mw-parser-output .cs1-hidden-error{display:none;font-size:100%}.mw-parser-output .cs1-visible-error{font-size:100%}.mw-parser-output .cs1-subscription,.mw-parser-output .cs1-registration,.mw-parser-output .cs1-format{font-size:95%}.mw-parser-output .cs1-kern-left,.mw-parser-output .cs1-kern-wl-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right,.mw-parser-output .cs1-kern-wl-right{padding-right:0.2em}
  2. ^ Dickinson, C.I. 1963. British Seaweeds. The Kew Series
  3. ^ a b c Norris, R.E. & Guiry, M.D. (2006-03-15). "Polysiphonia Greville 1823: pl. 90". AlgaeBase.
  4. ^ a b Stegenga, H., Bolton,J.J. & Anderson,R.J. (1997). Seaweeds of the South African West Coast. Bolus Herbarium Number 18.CS1 maint: Multiple names: authors list (link)
  5. ^ Abbott, I.A. & Hollenberg,G.J. (1976). Marine Algae of California. Stanford University Press, California. ISBN 978-0-8047-0867-8. OCLC 180623827.CS1 maint: Multiple names: authors list (link)
  6. ^ Newton, L. 1931. A Handbook of the British Seaweeds. British Museum
  7. ^ a b van den Hoek, C., Mann,D.G. & Jahns,M.H. (1995). Algae: An Introduction to Phycology. Cambridge University Press, Cambridge. ISBN 978-0-521-30419-1. OCLC 28182088.CS1 maint: Multiple names: authors list (link)
  8. ^ Parmentier,Jan (1999). "Polysiphonia, a red alga". Micscape Magazine.
  9. ^ von Sengbusch,Peter (2003-07-31). "Polysiphonia nigrescens". Botanik online. University of Hamburg.
  10. ^ Guiry,M.D. (2004-09-23). "Polysiphonia echinata Harvey". AlgaeBase.
  11. ^ Pedersén, M. E. E.; Roomans, G. M.; Hofsten, A. V. (1981). "Bromine in the Cuticle of Polysiphonia Nigrescens: Localization and Content". Journal of Phycology. 17: 105–108. doi:10.1111/j.0022-3646.1981.00105.x.
  12. ^ "Polysiphonia lanosa". Marine Life Information Network for Britain & Ireland.
  13. ^ Smith, G.M. 1955. Cryptogamic Botany Algae and Fungi. Volume 1. Second Edition. p.337
  14. ^ Dixon,P.D. (1973). Biology of Rhodophyta. Oliver & Boyd, Edinburgh. ISBN 978-0-05-002485-0. OCLC 944032.
  15. ^ Mondragon, J. & Mondragon, J. (2003). Seaweeds of the Pacific Coast. Sea Challengers, California. ISBN 978-0-930118-29-7. OCLC 50912900.

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Polysiphonia: Brief Summary

provided by wikipedia EN

Polysiphonia is a genus of filamentous red algae with about 19 species on the coasts of the British Isles and about 200 species worldwide, including Crete in Greece, Antarctica and Greenland. Its members are known by a number of common names. It is in the order Ceramiales and family Rhodomelaceae.

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