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Brown Algae or Phaeophyta Marine and multicellular
Sample of Protistan Diversity Brown Algae or Phaeophyta Marine and multicellular Brown or olive in color Structural and biochemical adaptations of seaweeds Live in tidal and intertidal regions so they need some strength, structure and desiccation protection to handle such environments. Structural Adaptations Thallus: body but lacks roots, stems and leaves Holdfast Stipe: stem like Blades: for PS
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Biochemical Adaptations
Sample of Protistan Diversity . Biochemical Adaptations Cell walls have cellulose and polysaccharides that give them a slimy feel and this protects them against hard surfaces during wave action. Ecological Import Food source Laminaria is in soup Red alga, Porphyra is the wrap in sushi Rich in iodine Algin in the algae is used to make agar, thickeners for pudding and salad dressing and of course oil drilling lubricants (but you probably already knew that.)
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Figure 28.20x2 Kelp forest
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Figure 28.20x1 Kelp forest Macrocystis is one kind in Monterey
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Some algae have life cycles that alternate generations Introduction
Sample of Protistan Diversity Some algae have life cycles that alternate generations Introduction What does it mean to “Alternate Generations?” During the life time of the organisms there exists multicellular stage when it is haploid and a multicellular stage when it is diploid. You see, humans have a haploid and a diploid stage but the haploid stage is not multicellular. Laminaria as an example (Fig ) Laminaria can easily be seen along the coast and what you are looking at is the sporophyte generation or 2N. The sporophyte produces spores which are 1N in sacs called sporangia. This is done by meiosis
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These gametophytes are much smaller than the sporophyte.
Sample of Protistan Diversity These spores can germinate into a male gametophyte or a female gametophyte. These gametophytes are much smaller than the sporophyte. The male gametophyte releases sperm while the female gametophyte produces eggs which remain on or attached to the gametophyte. The sperm must obviously swim to the eggs. This is thought to be aided by the use of a released chemical attractant. Sperm fertilize egg. This is called syngamy. We are now back to a 2N zygote. The zygote develops into the mature sporophyte on the female gametophyte where it was fertilized. Since the gameto- and sporophyte look different they are called heteromorphic.
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Figure 28.21 The life cycle of Laminaria: an example of alternation of generations
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Rhodophyta or Red Algae Red due to the pigment phycoerythrin.
Sample of Protistan Diversity Rhodophyta or Red Algae Red due to the pigment phycoerythrin. These algae can look rather purplish. They can be seen in Monterey as well as warmer waters. They absorb blue and green wavelengths that travel farther into the water so these algae can exist deeper.
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Figure 28.22 Red algae: Dulse (top), Bonnemaisonia hamifera (bottom)
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Chlorophyta or Green Algae
Sample of Protistan Diversity Chlorophyta or Green Algae The chloroplasts of green algae and those of plants are so similar that they are though to share a common ancestor. Fresh and Marine waters Lichens: a symbiotic (mutualistic) relationship between a fungi and a green alga. Example: Chlamydomonas, Volvox, Ulva, Spirogyra Unicellular or colonies or multicellular species
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Figure 28.23 Colonial and multicellular chlorophytes: Volvox (left), Caulerpa (right)
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Figure 28.x3 Spirogyra conjugating
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The use of pseudopodia for movement and feeding Introduction
Sample of Protistan Diversity The use of pseudopodia for movement and feeding Introduction So these protists can be heterotrophs since they use pseudopodia. Amoebas Unicellular and use pseudopodia Tip of the pseudopod gets anchored and then the cytoplasm streams towards this tip. Cytoskeleton of microtubules breaks down and reforms. Fresh and marine environments, soil Causes amoebic dysentery (Montezuma’s revenge)
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Actinopoda (Radiolarians)
Sample of Protistan Diversity Actinopoda (Radiolarians) Really slender pseudopodia called axopodia that gives these protists a “radiance.” Reinforced with microtubules the axopodia extend out, increase surface area and help with floatation. the axopodia can be used as a food capturing tool as microorganisms can stick to the axopodia and are then phagocytized.
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Figure 28.27 Actinopods: Heliozoan (left), radiolarian (right)
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Figure 28.27x Radiolarian skeleton
Skeletons of silica
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Porous shells (foramen = little hole) shells of calcium carbonate
Sample of Protistan Diversity Foraminifera Porous shells (foramen = little hole) shells of calcium carbonate cytoplasmic strands extend through the pores, increasing surface area. Some have a symbiotic relationship with an alga which live in the calcium carbonate shell.
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Mycetozoa or Slime Molds Introduction
Sample of Protistan Diversity Mycetozoa or Slime Molds Introduction they decompose dead organic matter. move by pseudopodia and feed by pseudopodia there are two main kinds of slime molds (just our luck) plasmodial cellular
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Plasmodial Slime Molds bright in color – yellow or orange
Sample of Protistan Diversity Plasmodial Slime Molds bright in color – yellow or orange the feeding stage is called a plasmodium which is an amoeboid mass. it is not multicellular; just a mass of cytoplasm engulfs food by phagocytosis Example: Physarum
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Figure 28.29 The life cycle of a plasmodial slime mold, such as Physarum
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Figure 28.29x1 Plasmodial slime mold
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Figure 28.1c Too diverse for one kingdom: a slime mold (Physarum polychalum)
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Example: Dictyostelium
Sample of Protistan Diversity Cellular Slime Molds feed as individual cells when food is present but will aggregate when food is depleted. cellular mass looks like a Plasmodial slime mold but there are cellular membranes. Haploid organisms Example: Dictyostelium
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Figure 28.30 The life cycle of a cellular slime mold (Dictyostelium)
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This is another “biggee.”
Sample of Protistan Diversity Multicellularity This is another “biggee.” A lot of these protists were unicellular but the unicellular eukaryotes gave way to multicellular adaptations that brought about a new explosion in diversity Fungi, plants and animals.
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