Lec5 Dinophyceae


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The Dinoflagellates

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Lec5 Dinophyceae

  1. 1. BIO 14 YA June 29, 2013
  2. 2. • Dinozoa or Pyrrophytes • 90% are marine plankton • ½ photosynthetic • Unicellular or in aggregations • symbiotic partners to sponges, corals, jellyfish and flatworms • primarily asexual, and reproduce by mitosis, only a few species have been found to reproduce sexually
  3. 3. • Cell covering is called Amphiesma that often forms plates • Made up mainly of cellulose • Grouped into two: • Armored/thecate • Unarmored/athecate
  4. 4. • Biflagellate • Longitudinal and transverse flagellum • Several thecal plates • Cingulum vs sulcus
  5. 5. • Commonly in reddish – blood red – deep red in color • Different species gives different water color • Can discolor water when in bloom
  6. 6. • Very diverse in size • Some have rigid walls others have none • Two types of dinoflagellates based on presence/absence of armor: armored and naked
  7. 7. • Some species of dinoflagellates (Gonyaulax, Pyrodinium, Pyrocystis, Noctiluca) are luminescent • They emit flashes of light in response to mechanical disturbance of the water. The light is produced by an enzymatic reaction
  8. 8. • Most of them are found in oceans (very few are freshwater). • Planktonic, few are benthic and some enter into symbiotic relationships. • Autotrophic-Heterotrophic forms. Parasites of invertebrates and fishes.
  9. 9. • Late summer, upwelling causes a burst of dinoflagellates (up to 20 million/liter), • Humans are influenced by contracting CIGUATERA and then PSP or paralytic shellfish poisoning • Saxitoxin – 100,000 times more potent then cocaine • Gessnerium monilatum is the most common PSP producer in the N. Atlantic
  10. 10. • SAXITOXIN (Alexandrium)-neurotoxin. • BREVETOXIN (Gymnodinium) • CIGUATOXIN (Gambierdiscus) – Ciguatera poisoning (eating contaminated fish) • OKADAIC ACID (Dinophysis)-causes DSP
  11. 11. Triassic to Pleistocene dinoflagellate zonations are correlated with: 1. Cretaceous to Tertiary planktonic foraminiferal and calcareous nanofossil zones 2. Jurassic and Cretaceous ammonite zones 3. An absolute time scale and sequence stratigraphy.
  12. 12. • Dinoflagellate cysts were first found in late Triassic rocks • Diverse and abundant cysts increase in Md. Jurassic • Cysts still occur in present marine sedimentary rocks and some non- marine strata • Stephanelytron redcliffense a Late Jurassic dinoflagellate cyst Late Jurassic cyst Systematophora penicillata
  13. 13. • This unique species of recent dinoflagellate is a “Fish Killer” • It produces a toxin which attacks the surface of fish • Once the toxin attacks the surface of the fish, P. piscicida feeds on the disaggregated and decomposing fish carcass
  14. 14. • Some photosynthetic dinoflagellates (Symbiodinium) are found in cells of many hosts like protozoa, clams, flatworms, jellyfish and corals.