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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