Dinophyta

DINOPHYTA
BIOL 202C
MARINE BOTANY
DINOPHYTA

Pigments - Chlorophyll-a and Chlorophyll-c, ß Carotene, several xanthophylls, Peridinin; Chlorophyll-b is never present.
Food reserves - Starch, lipids sometimes present.
Chloroplast - Thylakoids are mainly stacked in groups of three.
Cell wall - Usually made up of plates, contain cellulose and  sporopollenin.
Flagella - Usually present. Two in number.
DINOPHYTA
DESMOKONTS
Two anterior flagella. One flagellum is coiled over the cell surface.
Two large cell plates present.
DINOKONTS
One flagellum is ribbon-like and the other one extends back.
Thecal plates are variable in #.
desmokont
dinokont
STRUCTURE OF A DINOKONT
DINOFLAGELLATE CELL
Dinokaryotic nucleus – chromosomes are rod-shaped and remain condensed throughout the cell cycle. They lack histone proteins.
Trichocysts – vesicles containing crystalline rods and can be discharged to aid in defense.
Pusule – consists of series of vesicles and functions in osmoregulation.
REPRODUCTION
Asexual reproduction –zoospores and also by division of parent cell into two daughter cells.

Sexual reproduction - Two dinoflagellates will join together (called fusion). This stage is the planozygote stage. Then they change, sometimes quite dramatically, in shape and size. They get much bigger and they harden their shell. This stage is called hypnozygote. Then when the weather warms up, the cyst breaks out of its shell, forming a temporary stage called the planomeiocyte (not present in all species). This stage quickly becomes a normal dinoflagellate again.
SEXUAL REPRODUCTION
DINOFLAGELLATE 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.
DINOFLAGELLATE ECOLOGY
RED TIDE
Noctiluca bloom ---California
DINOFLAGELLATE ECOLOGY
RED TIDE
Florida Red Tide Bloom of Gymnodinium breve
DINOFLAGELLATE ECOLOGY
RED TIDE
North Carolina Sea Surface Temperature image of a Gymnodinium breve bloom
DINOFLAGELLATE ECOLOGY
BIOLUMINESCENCE
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.
BIOLUMINESCENCE
What is the advantage of bioluminescent
dinoflagellates?
DINOFLAGELLATE ECOLOGY
ZOOXANTHELLAE
Some photosynthetic dinoflagellates (Symbiodinium) are found in cells of many hosts like protozoa, clams, flatworms, jellyfish and corals. What is the advantage of this relationship?
TOXINS OF DINOFLAGELLATES
SAXITOXIN (Alexandrium)-neurotoxin.
BREVETOXIN (Gymnodinium)
CIGUATOXIN (Gambierdiscus) –Ciguatera poisoning (eating contaminated fishes)
OKADAIC ACID (Dinophysis)-causes DSP (diarrhetic shellfish poisoning)
FOSSIL DINOFLAGELLATES
Pierceites pentagonus
Cerodinium pannuceum
Isabelidinium sp