Seaweeds Net of Taiwan-flash menu

::: What are seaweeds? Morphology and Taxonomy Reproduction & Life cycles Ecology and distribution Importance and Economic uses Seaweed resources of Taiwan Seaweeds of northeastern Taiwan Search of species of Taiwan seaweeds sitmap Educational activity Game Extension learning Wallpaper
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icon Introduction
icon Morphology
  photo Appearance
photo Branching
photo Growth
photo Cell Structure
photo Plastid or Chloroplast
photo Holdfast
photo Asexual Reproduction
photo Sexual Reproduction
icon Taxonomy
  photo Chlorophyta
photo Phaeophyta
photo Rhodophyta
photo Cyanophyta
   
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taxonomy
Search of species of Taiwan seaweeds sitemap Educational activity Game Extension learning Wallpaper
iconPhaeophyta
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Phaeophyta  Algae placed in the phylum Phaeophyta (brown algae) are all multicellular. The simplest species has branched, filamentous body composed of uniseriate cells, such as the species placed in the order Ectocarpales. More advanced species may have differentiated structures that look like roots, stems and leaves. Some species, such as those in the order Laminariales, even have air bladders to help them floating on sea surfaces. They also have differentiated epidermis, cortical layer and medullar tissues. The species mentioned above usually have large thalli and they can grow up to 40~60 meters in height. Some of brown algae can form a marine forest (kelp-forest) or algae sea, attracting numerous marine organisms and drawing in abundant marine resources. Laminaria, one kind of kelps, tend to be distributed in cold waters. As the seawater temperature around Taiwan is usually warm (average temperature above 25℃), kelps are absent in Taiwan. However, Sargassum, a large body form of non kelp species, is common seen in Taiwan. In March and April, it is quite common to see small “Sargassum Seas” along the coast. Sargassum can grow up to 2 or 3 meters in height, so sampans passing by can be trapped by it.

Phaeophyta  Zoospores or gametes of brown algae have plastids, eye-spot, and two lateral flagella not equal in length. The forward-directed flagellum is long covered with hairlike appendages called mastigonemes. The backward-directed flagellum is short with sooth surface. Apart from chlorophyll a and c, β-carotene and lutein, brown algae usually contain an accessory yellowish pigment, fucoxanthin, so they tend to appear in brown. Their food reserve include oils, algin starch (Laminarin) and mannitol. Their cell walls are rich in alginate, so they tend to be colloidal or thick characters and are usually used to make food additives. They are also used in the textile industry, the paint industry, or other industrial uses. Many brown algae are edible. The most common ones include kelp, wakame and Petalonia binghaniae. As brown algae contain large quantities of vitamins and mineral salts, they are believed to be good dietary supplements. The use of brown algae in medicine dates back over a thousand years. It is written in several ancient Chinese medical books including “Compendium of Materia Medica” and “Shennong’s Classic of Materia Medica” that Undaria and Laminaria can help treat goiter, thyroid enlargement and oedema and that they induce urination. Modern medical research also shows that some brown algae can help lower blood pressure and prevent cancers. Scientists have actually used alginate to make anticoagulants, haemostatic medicine, blood volume expanders, hemostatic gauze, hemostatic sponge, medical imprints and base. In short, brown algae have high economic value.
Phaeophyta
  The classification of brown algae is mainly based on their forms and life histories. Basically, there are three subclasses:
  • Isogeneratae: Gametophytes and sporophytes of the species in this subclass have the same size and shape. Examples include Hincksia mitchellae, Padina minor, Dictyota divaricata.
  • Heterogeneratae: Gametophytes and sporophytes of the species in this subclass vary in their size and shape. Examples include Laminaria, Undaria, Ishige okamurae and Colpomenia sinuosa.
  • Cyclosporeae: the species in this subclass do not have clear alternation of generations. Their plant bodies are diploid (2N), which reproductive cells undergo meiosis when they produce gametes. Examples include Sargassum, Turbinaria ornata and Hormophysa cuneiformis.
  There are 10 families, 25 genus and 86 species of marine brown algae recorded from Taiwan. Cyclosporeae: the species in this subclass do not have clear alternation of generations. Their plant bodies are diploid (2N), which reproductive cells undergo meiosis when they produce gametes. Examples include Sargassum, Turbinaria ornata and Hormophysa cuneiformis.
 
 
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