lec5 dinophyceae
DESCRIPTION
The DinoflagellatesTRANSCRIPT
Dinophyceae(The Dinoflagellates)BIO 14 YAJune 29, 2013
What are Dinoflagellates?
• 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
Dinoflagellate structure• Cell covering is
called Amphiesma that often forms plates• Made up mainly of
cellulose • Grouped into two:•Armored/thecate•Unarmored/athecate
Dinoflagellate structure• Biflagellate• Longitudinal and
transverse flagellum• Several thecal
plates• Cingulum vs
sulcus
Parts of a Dinoflagellate Cell
Color • Commonly in
reddish – blood red – deep red in color• Different species
gives different water color• Can discolor water
when in bloom
Shape and Size • Very diverse in size• Some have rigid
walls others have none• Two types of
dinoflagellates based on presence/absence of armor: armored and naked
Plates of Armored Dinoflagellates
Reproduction among Dinoflagellates
Bioluminiscence• 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
What are the advantages of
bioluminescence?
Dinoflagellates Ecology• 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.
Red Tides• 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
TOXINS OF DINOFLAGELLATES• SAXITOXIN (Alexandrium)-
neurotoxin.• BREVETOXIN
(Gymnodinium)• CIGUATOXIN
(Gambierdiscus) –Ciguatera poisoning (eating contaminated fish)• OKADAIC ACID (Dinophysis)-
causes DSP (diarrhetic shellfish poisoning)
Palentological Significance
Triassic to Pleistocene dinoflagellatezonations 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.
Fossil Record• 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•
Stephanelytronredcliffense a Late
Jurassic dinoflagellatecyst
Late Jurassic cystSystematophorapenicillata
Fish Killer!• 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
Symbiosis• Some
photosynthetic dinoflagellates (Symbiodinium) are found in cells of many hosts like protozoa, clams, flatworms, jellyfish and corals.
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