module 8

• Algae


  • Composed of eukaryotic cells
  • May be single or multicellular, some occur as colonies or filaments, and some are coenocytic
  • Size varies from microscopic to giants (up to 75m in length)
  • Some are autotrophs (photosynthetic), some are heterotrophs (produce food thru carbon fixation), some ingest their food, some can do both photosynthesis and ingest their food, and some absorbs food in solution
  • Life cycle varies, but reproduction is generally by cell division and sexual processes
  • Most single-celled protists are motile (flagella), most multi-cellular protists are non-motile (though most can produce motile cells)
• Euglenophyta


  • Unicellular aquatic algae
  • Produce food by photosynthesis (chlorophyll a and b)
  • Reproduce asexually by cell division
  • Flexible outer covering (pellicle/periplast)
  • Can store paramylon (energy storage)
  • Has 2 flagella (one is short)
• Pyrrophyta


  • Fire algae or Dinoflagellates
  • Unicellular or colonial aquatic algae
  • Produce food by photosynthesis (chlorophyl a and c, xanthophyll (red) and fucoxanthin (special yellow-brown carotenoid)
  • Reproduce asexually by cell division
  • Covered with cellulose plates impregnated with silica
  • Food is stored as starch and oil
  • Has 2 flagella
• Gonyaulax which contains neurotoxin that are harmful to the marine fauna cause the "red tide" phenomenon
• Red tide phenomenon (Algal Bloom/Dinoflagellate Bloom)

  1. The population of dinoflagellates rise exponentially causing the waters to become orange, red, or brown

  2. This phenomenon is most likely to occur in warm waters of late summer and early fall

  3. A rise in the occurrence of red tides is presumed to be caused by human-produced coastal pollution that may have provided nutrients to the dinoflagellates causing deaths of several marine fauna and flora
• Phaeophyta


  • Multicellular algae that grow mostly on tropical and subtropical waters
  • Produce food by photosynthesis (chlorophyll a and c, and fucoxanthin (special yellow-brown carotenoid)
  • Reproduce asexually by production of spores, and sexually through the union of haploid gametophytes released from the spores
  • Kelp can grow more than 60m in length
  • Rockweed can grow on rocks
  • Has 2 flagella on reproductive cells
  • Produce Algin which is used in making ice cream, lotion, and plastics
  • Contains vitamins and minerals (iodine) which can be made into antiseptics such as the Tincture of Iodine
• Chlorophyta


  • May be unicellular, colonial, siphonous (tubular), or multicellular
  • Most are flagellated but some are non-motile
  • Produce food by photosynthesis (chlorophyl a and c, and carotenoid (orange color)
  • Reproduction is highly variable
  • Cell walls are made of cellulose and pectin
  • Food is stored as starch (pyrenoids)
  • Sheet-like body (Thallus)
  • Spirogyra (water silk) grow as a unicellular green thread or filament
• Rhodophyta


  • Multicellular eukaryotic algae that are mostly found in tropical marine locations
  • Lack flagella (non-motile) and centrioles
  • Produce food by photosynthesis (chlorophyl a and c, and carotenoid (orange color)
  • Reproduce asexually by monospores carried by water currents until germination
  • Cell walls are made up of cellulose and different types of carbohydrates
  • Can grow in solid surfaces of tropical reefs or attaches to other algae
  • Produces polysaccharides: Agar - used as food thickener and culture medium, Carragenan - food additive used to stabilize chocolate milk, cosmetics and paints; provide thick creamy texture to ice creams and other soft processed food